path: root/Master/texmf-dist/source/latex/pdfmanagement-testphase/l3pdffield.dtx

% \iffalse meta-comment
%
%% File: l3pdffield.dtx
%
% Copyright (C) 2021-2022 The LaTeX Project
%
% It may be distributed and/or modified under the conditions of the
% LaTeX Project Public License (LPPL), either version 1.3c of this
% license or (at your option) any later version.  The latest version
% of this license is in the file
%
%    http://www.latex-project.org/lppl.txt
%
% This file is part of the "LaTeX PDF management testphase bundle" (The Work in LPPL)
% and all files in that bundle must be distributed together.
%
% -----------------------------------------------------------------------
%
% The development version of the bundle can be found at
%
%    https://github.com/latex3/pdfresources
%
% for those people who are interested.
%
%<*driver>
\RequirePackage{pdfmanagement-testphase}
\DocumentMetadata{}
\documentclass{l3doc}
\usepackage{array,booktabs,caption}
\usepackage{l3pdffield-testphase,tikz}
\hypersetup{pdfauthor=The LaTeX Project,
 pdftitle=l3pdffield (LaTeX PDF management testphase bundle)}
\begin{document}
  \DocInput{\jobname.dtx}
\end{document}
%</driver>
% \fi
% \NewDocElement[
%   idxgroup=checkbox keys,
%   idxtype = {checkbox key},
%   printtype= \textit{checkbox key}
%    ]{Checkboxkey}{checkboxkey}
%  \NewDocElement[
%   idxgroup=field keys,
%   idxtype = {field key},
%   printtype= \textit{field key}
%    ]{Fieldkey}{fieldkey}
%  \NewDocElement[
%   idxgroup=setup keys,
%   idxtype = {setup key},
%   printtype= \textit{setup key}
%    ]{Fieldsetupkey}{fieldsetupkey}
%  \NewDocElement[
%   idxgroup=annot keys,
%   idxtype = {annot key},
%   printtype= \textit{annot key}
%    ]{Annotkey}{annotkey}%
% \providecommand\hook[1]{\texttt{#1}}
% \title{^^A
%   The \pkg{l3pdffield} module\\ Commands to create form fields   ^^A
%   \\ \LaTeX{} PDF management testphase bundle
% }
%
% \author{^^A
%  The \LaTeX{} Project\thanks
%    {^^A
%      E-mail:
%        \href{mailto:latex-team@latex-project.org}
%          {latex-team@latex-project.org}^^A
%    }^^A
% }
%
% \date{Version 0.95m, released 2022-03-17}
%
% \maketitle
% \begin{documentation}
% \section{\pkg{l3pdffield} Introduction}
% The implementation of form fields in hyperref has some bugs\footnote{see for example
% \url{https://github.com/latex3/hyperref/issues/94}}. This package is a first step
% towards the goal to review and improve the code of form fields.
%
% Like the \pkg{pdfmanagement-testphase} package itself it is a temporary package:
% the definite home of the code is not yet decided, and during the development
% changes in the interfaces are possible.
%
% The package itself is currently loaded with
% \begin{verbatim}
% \usepackage{l3pdffield-testphase}
% \end{verbatim}
%
% The source code is splitted into various submodules. All code is combined in the
% sty, but the documentation is in individual PDF.
% \begin{description}
% \item[\texttt{l3pdffield}] This contains the basic commands and keys
%  to create a form field.
% \item[\texttt{l3pdffield-checkbox}]  The code to created checkboxes.
% \item[\texttt{l3pdffield-textfield}] The code to created text fields.
% \item[\texttt{l3pdffield-radiobutton}] The code to create radio buttons.
% \item[\texttt{l3pdffield-pushbutton}] The code to create push buttons.
% \item[\texttt{l3pdffield-choice}] The code to create choice fields (lists and drop-down/combo
% fields.
% \item[\texttt{l3pdffield-action}]
% Code related to actions, mostly submit and reset actions.
% \item[\texttt{l3pdffield-signature}] (not done yet) Code for signature fields
% \item[Form initialization] (not done yet) The |\Form| command/environment
% of \pkg{hyperref} initialize a few things like fonts
% for text fields which should be moved. It is not strictly necessary to
% have this code, most examples works without it, but in case of problems it is
% possible to do the initialization by using the \pkg{hyperref} command.
% \end{description}
%
% The code requires the new PDF management. The code makes use of
% \pkg{l3pdfxform} to create the form Xobjects of the appearances.
% This code doesn't support yet the the dvips backend.
%
% The code targets PDF~2.0. This doesn't mean that it won't work in older
% PDF versions, but it tries to implement requirements needed or recommended
% for 2.0; most importantly appearances are used by default everywhere and it
% deprecates |/NeedAppearances|.
%
% Please keep in mind
% \begin{itemize}
% \item Not every PDF viewer supports form fields or all types and features.
% \item The handling can depend on settings in the PDF viewer. In adobe reader for
% example I had to disable an option to avoid that it tries to create an appearance
% itself.
% \item Standards like pdf/A disable some features of form fields like javascript actions
%  (as you typically can't change the PDF).
% \end{itemize}
%
% If \pkg{hyperref} is loaded before
% the package will suppress the deprecated |/NeedAppearances| setting. If \pkg{hyperref}
% is loaded later you should do it in the \cs{Form} options.
%
% So a typical use together with hyperref could look like this
%
% \begin{verbatim}
% \RequirePackage{pdfmanagement-testphase}
% \DocumentMetadata{uncompress}
% \documentclass{article}
% \usepackage{hyperref}
% \usepackage{l3pdffield-testphase}
% \begin{document}
% \Form
% \end{verbatim}
%
% \section{Some background}
%
% A document can contain a arbitrary number of fields which can be organized in trees.
% The leaf fields in such a tree, the \emph{terminal fields}, typically have
% widget annotations as kids which are then the actual, visual instances of the field,
% and allow to interact with the field. I will call such a
% tree a \emph{fieldset}, nodes \emph{fields} and the widget annotation
% \emph{field annotations}.
%
% If a field has only one child annotation the content of the field dictionary and the
% widget annotation dictionary can be merged---some examples in the PDF reference
% show such merged dictionaries---but the code here keeps them separate, at the end
% this is clearer.
%
% A simple example would look like this
%
%  \begin{tikzpicture}[level 2/.style={level distance=7mm},
%  level 1/.style={sibling distance=25mm},
%  level 2/.style={sibling distance=15mm}]
%   \node[draw] {week}
%   child {node[draw] {mon}
%           child {node[draw,dashed] {annot}}
%         }
%   child {node[draw] {tue}
%          child {node[draw,dashed] {annot}}
%         }
%   child {node[draw] {wen}
%           child {node[draw,dashed] {annot}}
%           child {node[draw,dashed] {annot}}
%         }
%   ;
%   \end{tikzpicture}
%
% In many cases a fieldset consists of only one field along with its field annotation(s),
% but larger sets can be needed to build more complex interactions with javascript code.
% For example a datepicker can be built as a fieldset with various fields to represent
% the month and year choice and to select days.
%
% Fields in a fieldset should have a name, for example |wen| or |week| in the example
% above. This name is the \emph{partial name} of the field, the \emph{full name}
% is than built from it by adding the names of the parents separated by periods.
% In the example above the partial name is \texttt{mon} and the full name
% \texttt{week.mon}.
% Partial names shouldn't contain periods. If two fields have the same name they will
% work in unison: if you enter text in one field, the text appears also in the other, such
% fields must have the same type and the same value and default value entry.
% If a field has no name it is considered to be a simple widget annotation and so
% only another representation of its parent.
%
%
% All terminal fields should also have a type, e.g. \texttt{Btn} for a button field,
% or \texttt{Tx} for a textfield. The type can be set for the parent and then inherited.
% The fields in a fieldset can have different types.
%
% \subsection{The look of a field: Appearances and other settings}
%
% The look of widget annotation of a field can be set with various keys. The keys developed over
% time and some of them superseed older ones. There is for example the simple
% |/Border|, the more sophisticated |/BS| (\enquote{border style dictionary}),
% the \enquote{dynamic appearance dictionary} |MK|, with lots of keys,
% and the appearance dictionary |/AP| which
% may define as many as three separate appearances:
% the normal appearance (required), the rollover appearance and the down appearance.
% Such an appearance can be a simple form XObjects%
%   \footnote{Such form XObjects are small pictures stored in the PDF which
%       can be referenced in various part of the PDF. They can be
%       created with the commands of the \pkg{l3pdfxform} package.}%
% , but in some cases the annotation can have different \emph{appearance states}:
% a checkbox
% for example can be checked or unchecked, in this case the appearances
% are dictionaries which
% maps state names like |/Yes| and |/Off| to form XObjects.
%
% The annotations cover a rectangular area on
% the page and form XObjects appearances are squeezed into this rectangle.
% So for the best result
% both should have the same ratio of width and height. Simple plain backgrounds can
% also be created in large size and reused for various annotations.
% Form XObjects used as appearances can not be rotated, if needed one has to
% create a new appearance.
%
%
% In PDF 2.0 widget annotations must have at least a normal |/AP| appearance
% (unless the size  of the annotation is zero) and the keys \enquote{\itshape C, IC, Border,
% BS, BE, BM, CA, ca, H, DA, Q,
% DS, LE, LL, LLE, and Sy shall be ignored}. But it is quite unclear if
% PDF Viewer honor this, and if this make sense e.g. for text fields which require
% a DA entry. It is also not clear how appearances and the entries of the MK dictionary
% are related in a form field.  Tests with some PDF viewers
% are needed here.
%
% \subsection{Tagged PDF}
%
% Field annotations are (like link annotations) not part of the page stream. But
% they are obviously nevertheless meaningful content and must be consider if
% a PDF is \enquote{tagged}, that means if a structure is added.
%
% According to the PDF references fields should be tagged by adding a |Form| structure
% element containing the object reference to a field annotations. Fields with more than
% one annotation like radio buttons need a |Form| structure for every one.
% Additional some cross references to structure relevant object like the parent tree
% are needed, for more info check the documentation of the \pkg{tagpdf} package.
%
% The commands of this module already contain the needed support. So if
% \pkg{tagpdf} is used and tagging activated the fields will be added as |Form| element
% to the structure where they are created. It is possible to deactivate tagging for
% a field annotation by setting the |tag| to false as described below.
%
% If lualatex is used tagging require either that \pkg{tagpdf} is used with the
% option |global-mc|, or mc-chunks must be correctly closed manually, as the automatic
% code can't escape the grouping.
%
% It is recommended to use the |TU|/|altname| key to give the field a readable
% name.
%
%
% \section{Commands}
% \begin{function}{\pdffield_field:nn,\pdffield_field:Vn}
% \begin{syntax}
%  \cs{pdffield_field:nn}\Arg{key val list}\Arg{field ID}
% \end{syntax}
% This creates a new field. \meta{field ID} will be used to create and
% reference the needed objects but it is not the direct object name, so
% |pdf_object_ref:n| can not be used to access (and there will not
% clash with object names). It is recommended to start
% the name with a module prefix to avoid name clashes, so e.g. |mymodule/field/1| or
% |mymodule/field/week|.
%
% The list of handled keys is described below.
% Typically the \meta{key val list} should at least set the name |T|, fields that
% are kids in a fieldset must set the |parent| key, this should point to a field
% declared before.
%
% The command is meant as a basic command to build more complex variants like
% checkbox or textfields. For this reason it doesn't check if
% the combination of values and flags are sensible, and it uses as key names the
% names from the PDF reference.
% If you create a button field (Btn) and set MaxLen (which is only known for text
% fields), it will not complain.
%
% Root fields (fields without parent) are added automatically to the
% Catalog/AcroForm dictionary with
%
%
% \begin{verbatim}
% \pdfmanagement_add:nnx{Catalog/AcroForm}{Fields}{<obj ref>}
% \end{verbatim}
%
% \end{function}
%
% \begin{function}{\pdffield_annot:n,\pdffield_annot:V}
% \begin{syntax}
%  \cs{pdffield_annot:n}\Arg{key val list}
% \end{syntax}
% This creates a new field annotation.
% It is a widget annotation box created with \cs{pdfannot_widget_box:nnn}, and
% it is possible to add values to its dictionary
% by using |\pdfannot_dict_put:nnn {widget}...|.
% But to correctly setup the parent/kid relationship some additional wrapper code is needed.
% The command also setup dictionaries to fill the |AP|, |MK| and |AA| dictionaries.
% \end{function}
%
% \begin{function}{\pdffield_annot_ref_last:}
% \begin{syntax}
%  \cs{pdffield_annot_ref_last:}
% \end{syntax}
% If a tagged PDF should be created, the object
% of the annotation of a field should be referenced in the Form structure element.
% This command allows to retrieve the reference to this object.
% \end{function}

% \begin{function}{\pdffield_appearance:nn}
% \begin{syntax}
%  \cs{pdffield_appearance:nn}\Arg{name}\Arg{content}
% \end{syntax}
% This is a small wrapper around \cs{pdfxform_new:nnn} (which could be used too)
% to create an appearance. To avoid name clashes \meta{name} should start with
% a module part, e.g. |mymodule/appearance/cross|.
% \end{function}
%
% \begin{function}{\pdffield_setup:n}
% \begin{syntax}
%  \cs{pdffield_setup:n}\Arg{key-val}
% \end{syntax}
% This command allows to preset some field settings.
% \end{function}
% It knows currently two keys:
%
% \begin{function}{create-style}
% \begin{syntax}
%  |create-style| = \Arg{name}\Arg{key-val}
% \end{syntax}
% This defines a style which can then be used with the |style| key.
% \Arg{key-val} can be an arbitrary collection of the keys of the module.
% \end{function}
%
% \begin{function}{style}
% \begin{syntax}
%  |style| = \Arg{style}
% \end{syntax}
% This uses a style define with the previous |create-style|.
% \end{function}
%
% \begin{function}{preset-checkbox}
% \begin{syntax}
% |preset-checkbox|=\Arg{key-val}
% \end{syntax}
% This allows to set default keys for a checkbox.
% \end{function}
%
% \begin{function}{preset-radio}
% \begin{syntax}
% |preset-radio|=\Arg{key-val}
% \end{syntax}
% This allows to set default keys for a radio button.
% \end{function}
%
% \begin{function}{preset-textfield}
% \begin{syntax}
% |preset-textfield|=\Arg{key-val}
% \end{syntax}
% This allows to set default keys for a text field.
% \end{function}
%
% \section{Special keys}
%
% \begin{function}{value,default}
% \begin{syntax}
% |value|  =\Arg{value}\\
% |default|=\Arg{value}
% \end{syntax}
% These two keys pass the value to a handler which can be redefined.
% Their exact behaviour depends on field type. Please check their documentation.
% \end{function}
%
% \section{Field Keys}
%
% Table~\ref{tab:fieldkeys} summarize the keys which can be used.
% A number of keys have two names, the second is normally the name used by hyperref.
% Where is makes sense an empty value \enquote{unsets} a key.
%
% \begin{table}
% \caption{Keys for fields}\label{tab:fieldkeys}
% \centering
% \begin{tabular}{>{\ttfamily}lllll}
% \toprule
% key      & value      & required & inheritable &remark\\\midrule
% parent   & field ID   & for non-root fields &     \\
% style    & style name &                   & defined with |create-style| \\
% T, name        & string   & mostly   &             \\
% TU, altname       & string   &          &             \\
% TM, mappingname       & string   &          &             \\
% FT       & name     & terminal fields & yes  \\
% setFf,    & list of flags &     & yes\\
% setfieldflags\\
% unsetFf,  & list of flags &    & yes \\
% unsetfieldflags \\
% V        & various   &        & yes \\
% DV       & various   &        & yes \\
% MaxLen   & integer   & with Comb   & yes             & only textfields\\
% Lock     & object name &         &                  & signature field\\
% SV       & object name &         &                  & signature field\\
% Opt      & object name &         &                  & buttons and choice fields\\
% TI       & integer    &          &                  & list fields\\
% I        & object name&          &                  & list fields\\
% AA/K, keystroke     & javascript \\
% AA/F, format     & javascript\\
% AA/V, validate     & javascript\\
% AA/C, calculate     & javascript\\
% DA        & string    & yes   &   yes    & variable text \\
% Q       & 0, 1 or 2   &          & yes   &variable text  \\
% DS       &    &          &         & (ignored) \\
% RV       &  &  &        & (ignored) \\\bottomrule
% \end{tabular}
% \end{table}
%
% \begin{function}{parent}
%  \begin{syntax}
%   |parent| = \meta{field ID}\\
%  \end{syntax}
% This declares the parent of the field. It is required if
% the field is not the root of the fieldset. The value is the field ID
% of the parent, the parent should have been already declared.
% It will add the reference to the parent field to the |/Parent| key, and also
% add reference of the kid as |/Kid| in the parent field.
% \end{function}
%
% \begin{function}{name,T}
%  \begin{syntax}
%   |name| = \meta{partial name}\\
%   |T| = \meta{partial name}
%  \end{syntax}
% This sets the partial name of the field. It shouldn't contain
% a period, be not empty and sensibly consist of simple ascii chars.
% It is normally required, see above. The value is passed through \cs{pdf_string_from_unicode:nnN}.
% \end{function}
%
% \begin{function}{altname,TU}
%  \begin{syntax}
%   |altname| = \meta{string}\\
%   |TU| = \meta{string}\\
%  \end{syntax}
% This sets an alternative name for user interaction.
% Unlike the name field it can use unicode or periods.
% The value is passed through \cs{pdf_string_from_unicode:nnN}
% \end{function}
%
% \begin{function}{mappingname,TM}
%  \begin{syntax}
%   |mappingname| = \meta{string}\\
%   |TM| = \meta{string}\\
%  \end{syntax}
% This sets an alternative name for the export.
% The value is passed through \cs{pdf_string_from_unicode:nnN}
% \end{function}
%
% \begin{function}{FT}
%  \begin{syntax}
%   |FT| = |Btn|\verb"|"|Tx|\verb"|"|Ch|\verb"|"|Sig|
%  \end{syntax}
% This sets the type of the field, the value should be one of
% \texttt{Btn} (button), \texttt{Tx} (text), \texttt{Ch} (choice),  \texttt{Sig} (signature).
% The value is of relevance only for terminal fields, but it can be set in a parent
% and then inherited.
% \end{function}
%
% \begin{function}{setfieldflags,setFf,unsetfieldflags,unsetFf}
%  \begin{syntax}
%   |setfieldflags| = \meta{comma list of flags}\\
%   |setFf| = \meta{comma list of flags}\\
%   |unsetfieldflags| = |all| \verb"|" \meta{comma list of flags}\\
%   |unsetFf| = |all| \verb"|" \meta{comma list of flags}
%  \end{syntax}
%  These keys accept a list of flag names and then sets or unsets them, the resulting value
% is then used with the \texttt{/Ff} key. Depending
% on the field type some flags must be set or unset, other are optional or are ignored.
% The flag name can be given in PDF spelling (\texttt{RadiosInUnison}),
% in lowercase (\texttt{radiosinunison}), and as number. |unsetFf| and its
% alias |unsetfieldflags|  know the special value |all| which clears all the fields.
%
% The list of flags are:
% |ReadOnly|, |Required|,
% |NoExport|, |Multiline|, |Password|,    |NoToggleToOff|, |Radio|, |Pushbotton|,
% |Combo|, |Edit|,   |Sort|, |FileSelect|,  |MultiSelect|, |DoNotSpellCheck|,
% |DoNotScroll|, |Comb|,  |RadiosInUnison|, |RichText|, |CommitOnSelChange|.
%
% \end{function}
%
% \begin{function}{V}
%  \begin{syntax}
%   |V| = \meta{various}
%  \end{syntax}
% This sets the value of the field. Its
% format varies depending on the field type, so typically
% commands for the various type will have to preprocess and sanitize it.
% The value given here is x-expanded and then added to the dictionary!
% See the descriptions of individual field types for further information.
% (Pushbuttons for example don't have a value).
% \end{function}
%
% \begin{function}{DV}
%  \begin{syntax}
%   |DV| = \meta{various}
%  \end{syntax}
% The default value, to which the field reverts
% when a reset-form action is executed. The format of this value is the
% same as that of \texttt{DV}.
% \end{function}
%
% \begin{function}{MaxLen}
%  \begin{syntax}
%   |MaxLen| = \meta{integer}
%  \end{syntax}
% Only relevant for textfields.
% The value is an integer and describes the maximum length of the field’s text in characters.
% Required if the |Comb| flag is used.
% \end{function}
%
% \begin{function}{Lock}
%  \begin{syntax}
%   |MaxLen| = \meta{object name}
%  \end{syntax}
% Only relevant for signature fields. The value is an object name
% which should point to a dictionary that specifies a set of form fields
% that shall be locked when this signature field is signed. The exact format of
% the dictionary is described in the PDF reference.
% \end{function}
%
% \begin{function}{SV}
%  \begin{syntax}
%   |SV| = \meta{object name}
%  \end{syntax}
% Only relevant for signature fields. The value is an object name
% which should point to a seed value dictionary. The exact format of
% the dictionary is described in the PDF reference.
% \end{function}
%
% \begin{function}{Opt}
%  \begin{syntax}
%   |Opt| = \meta{object name}
%  \end{syntax}
% Only relevant for checkboxes, radiobuttons and choice fields.
% The value is an object name
% which should point to a array. The exact format of
% the array is described in the PDF reference.
% \end{function}
%
% \begin{function}{TI}
%  \begin{syntax}
%   |TI| = \meta{integer}
%  \end{syntax}
% Only relevant for scrollable list boxes.
% The value is an integer, the top index (the index in the Opt array
% of the first option visible in the list). Default value: 0
% \end{function}
%
% \begin{function}{I}
%  \begin{syntax}
%   |I| = \meta{object name}
%  \end{syntax}
% For choice fields that allow
% multiple selection (MultiSelect flag set). The value is an object name
% which should point to a array. The exact format of
% the array is described in the PDF reference
% (I have no idea what exactly should be added there, perhaps some future test will make
% it more understandable.)
% \end{function}
%
% The following four keys are used to add javascript (\enquote{ECMAScript}) code.
% The values are expanded. It is recommended to store
% the javascript in a stream object and to pass the object reference, but passing
% a string (including parentheses) is possible too.
% The keys will be ignored if a pdfstandard
% is used that prohibits such actions.
%
% \begin{function}{AA/K,keystroke}
%  \begin{syntax}
%   |AA/K| = \meta{ECMAScript}\\
%   |keystroke| = \meta{ECMAScript}
%  \end{syntax}
% This adds a keystroke action to the
% additional action dictionary. The action is meant for text and choice fields.
% It is quite unclear if such an action
%  make sense for non-terminal fields.
%  \end{function}
%
% \begin{function}{AA/F,format}
%  \begin{syntax}
%   |AA/F| = \meta{ECMAScript}\\
%   |format| = \meta{ECMAScript}
%  \end{syntax}
% This adds a format action to the
% additional action dictionary. The action is meant for text and choice fields.
% It is quite unclear if such an action
%  make sense for non-terminal fields.
% \end{function}
%
% \begin{function}{AA/V,validate}
%  \begin{syntax}
%   |AA/V| = \meta{ECMAScript}\\
%   |validate| = \meta{ECMAScript}
%  \end{syntax}
% This adds a validate action to the
% additional action dictionary. It is quite unclear if such an action
%  make sense for non-terminal fields.
%  \end{function}
%
% \begin{function}{AA/C,calculate}
%  \begin{syntax}
%   |AA/C| = \meta{string (ECMAScript)}\\
%   |calculate| = \meta{string (ECMAScript)}
%  \end{syntax}
% This adds a calculate action to the
% additional action dictionary. It is quite unclear if such an action
% make sense for non-terminal fields.
% If an calculate action is used, the field will be added to the
% AcroForm/CO array to define the calculation order. The order can
% be controlled through the following key |sortkey|.
% \end{function}
%
%  \begin{function}{sortkey}
%  \begin{syntax}
%   |sortkey| = \meta{string}
%  \end{syntax}
% This sets a sortkey for fields with calculate action.
% The sortkeys are sorted lexically with |\str_compare:nNnTF|.
% fields without sortkey will get an empty sortkey and so be at the begin,
% the order of fields with the same sortkey is not defined.
% The module only sorts fields created with the commands of this module, the
% sorting of fields created by \pkg{hyperref} is independant.
% \end{function}
%
% \begin{function}{DA}
%  \begin{syntax}
%   |DA| = \meta{string}
%  \end{syntax}
% This contains instructions for the text in text fields.
% It is stored expanded and parentheses are added around the value.
% \end{function}
%
% \begin{function}{Q,align}
%  \begin{syntax}
%   |Q| = |left|\verb"|"|center|\verb"|"|right|\\
%   |align| = |left|\verb"|"|center|\verb"|"|right|
%  \end{syntax}
% The justification of the text.
% \end{function}
%
% \begin{function}{DS,RV}
% These two keys are currently not implemented
% as it is unclear if there are of any use.
% \end{function}
%
% \begin{function}{fieldID}
%  \begin{syntax}
%   |fieldID| = \meta{field ID}\\
%  \end{syntax}
% \emph{For experts only!}
% This stores \meta{field ID} in an internal variable.
% The variable is not used by the basic commands,
% but by the commands to create the various field types.
% Check their documentation for use cases.
% \end{function}
% \section{Annot keys}
%
% Table~\ref{tab:annotkeys} summarize the keys which can be used.
% A number of keys have alias names which are mentioned in the descriptions.
%
% \begin{table}
% \caption{Keys for field annotations}\label{tab:annotkeys}
% \centering
% \begin{tabular}{>{\ttfamily}lllll}
% \toprule
% key      & value      & required &remark\\\midrule
% parent   & field ID & yes             \\
% width    & dim expression & (yes)  & default is 0pt \\
% height   & dim expression & (yes)  & default is 0pt \\
% depth   & dim expression & (yes)  & default is 0pt \\
% AP/N    & appearance name  & yes  (in PDF 2.0) \\
% AP/R    & appearance name  & yes  (in PDF 2.0) \\
% AP/D    & appearance name  & yes  (in PDF 2.0) \\
% AS      & name  & yes  (in PDF 2.0) \\
% setF    & list of flags \\
% unsetF  & list of flags \\
% AA/*    & javascript   & *= F, Bl, D, U, E, \\
%         &              &    X, PO, PC,PV, PI\\
% MK/*    & various      & *= R, BC, BG, CA, RC, \\
%         &              &   AC, I, RI, IX, IF, TP\\ \bottomrule
%
% \end{tabular}
% \end{table}
%
% \begin{function}{width,height,depth}
% \begin{syntax}
% |width| = \meta{dim expression}\\
% |height| = \meta{dim expression}\\
% |depth| = \meta{dim expression}
% \end{syntax}
% These keys allow to set the dimensions of the annotation.
% The value should be a command that expands to a dimension expression. By default
% all values are zero.
% \end{function}
%
% \begin{function}{tag}
%  \begin{syntax}
%   |tag| = |true|\verb+|+|false|
%  \end{syntax}
% This key is related to tagging and enables/disables the tagging.
% \end{function}
%
% \begin{function}{parent}
%  \begin{syntax}
%   |parent| = \meta{field ID}\\
%  \end{syntax}
% This sets the parent. The value should be field ID of
% an already declared field.
% \end{function}
%
% \begin{function}{AP/N,appearance,AP/R,rollover-appearance,AP/D,down-appearance}
%  \begin{syntax}
%   |AP/N| = \meta{appearance name}\\
%   |appearance| = \meta{appearance name}\\
%   |AP/R| = \meta{rollover appearance name}\\
%   |rollover-appearance| = \meta{rollover appearance name}\\
%   |AP/D| = \meta{down appearance name}\\
%   |down appearance| = \meta{down appearance name}\\
%  \end{syntax}
% This keys set the normal, rollover and down appearance. The names
% |appearance|, |rollover-appearance| and |down-appearance| are aliases.
% The value is by default a simple name of an appearance/form Xobject but
% modules like \pkg{l3pdffield-checkbox} change this to allow to add appearances for
% various states. So check the documentation for the various field types for the
% exact format of the value.
% \end{function}
%
% \begin{function}{AS}
%  \begin{syntax}
%   |AS| = \meta{appearance state name}
%  \end{syntax}
% This key sets the default appearance state.
% The value is a name \emph{without} the starting slash
% (it is passed through |\pdf_name_from_unicode_e:n|),
% for checkbox for example |Yes|. If used it should typically have the same value
% as the V and DV key of the field.
% \end{function}
%
%\begin{function}{setannotflags,setF,unsetannotflags,unsetF}
%  \begin{syntax}
%   |setannotflags| = \meta{comma list of flags}\\
%   |setF| = \meta{comma list of flags}\\
%   |unsetannotflags| = |all| \verb"|" \meta{comma list of flags}\\
%   |unsetF| = |all| \verb"|" \meta{comma list of flags}
%  \end{syntax}
% These keys allow to set or unset the annot flags.  They expect a comma lists of
% flag names. Allowed names |Invisible|, |Hidden|,
%  |Print|, |NoZoom|,|NoRotate|, |NoView|, |ReadOnly|, |Locked|, |ToggleNoView|,
%  |LockedContents|, or the lowercase variants or numbers.
% \end{function}
%
% \begin{function}{AA/*}
%  \begin{syntax}
%  |AA/*| = \meta{ECMAScript}
%  \end{syntax}
% * should be one of |Fo|, |Bl|, |D|, |U|, |E|, |X|, |PO|, |PC|, |PV|, |PI|.
% Alias names for the first six keys are
% |onfocus|, |onblur|, |onmousedown|, |onmouseup|, |onenter|,  |onexit|.
% These keys adds then the respective key to the |/AA| dictionary
% of the field annotation object.
% Their value should be javascript code. The value is expanded but not escaped.
% It is recommended to
% store the code in a stream object and to use the object reference as value.
% The |/AA| dictionary
% is suppressed if a pdf/A standard is set.
%
% For example
% \begin{verbatim}
%    onenter={(app.alert('Hello');)}
% \end{verbatim}
% \end{function}
%
% The following keys add values to the  \emph{dynamic appearance dictionary}
% |MK| directory. This is only relevant for
% annotations with dynamic content, like e.g. textfields.
% The settings can also affect checkboxes and radio buttons if the (deprecated)
% |NeedAppearances| is set to true.
%
% The |MK| dictionary can also be added by using |\pdfannot_dict_put:nnn{Widget}{MK}{...}|
% but the two methods should not be mixed.
%
%  \begin{function}{MK/R,rotate}
%  \begin{syntax}
%  |MK/R| = |0| \verb"|" |90| \verb"|" |180| \verb"|" |270|\\
%  |rotate| = |0| \verb"|" |90| \verb"|" |180| \verb"|" |270|
%  \end{syntax}
% These rotates the content of the annotation.
% \end{function}
%
% \begin{function}{MK/BC,bordercolor}
%  \begin{syntax}
%  |MK/BC| = \meta{color expression} \verb"|" [\meta{model}]\Arg{values}\\
%  |bordercolor| = \meta{color expression} \verb"|" [\meta{model}]\Arg{values}
%  \end{syntax}
% These colors the border. Internally currently RGB is used.
% The colors used in
% \meta{color expression} must be known to the \pkg{l3color} commands.
% \end{function}
%
% \begin{function}{MK/BG,backgroundcolor}
%  \begin{syntax}
%  |MK/BG| = \meta{color expression} \verb"|" [\meta{model}]\Arg{values}\\
%  |backgroundcolor| = \meta{color expression} \verb"|" [\meta{model}]\Arg{values}
%  \end{syntax}
% These colors the background. Internally currently RGB is used.
% The colors used in
% \meta{color expression} must be known to the \pkg{l3color} commands.
% \end{function}
%
% \begin{function}{MK/CA,caption}
%  \begin{syntax}
%  |MK/CA| = \meta{string}\\
%  |caption| = \meta{string}
%  \end{syntax}
% This sets a text for the caption. \meta{string} is passed through \cs{pdf_string_from_unicode:nnN}
% and parentheses are added automatically. The font used seems to depend on
% the whims of the PDF reader: At least for checkboxes adobe reader quite insists to
% always use a symbol font and not a text font. It also shows always
% only one symbol, regardless how much one put in the string.
% hyperref uses the key names |checkboxsymbol| and
% |radiosymbol| for this setting.
% \end{function}
%
% \begin{function}{MK/RC,rollover-caption}
%  \begin{syntax}
%  |MK/RC| = \meta{string}\\
%  |rollover-caption| = \meta{string}
%  \end{syntax}
% This sets a text for the rollover-caption. \meta{string} is passed through \cs{pdf_string_from_unicode:nnN}
% and parentheses are added automatically. The key should be used only with
% pushbuttons. It is unclear if is actually used by the PDF viewer, but the
% pushbuttons modules uses the argument also to setup the appearance.
% \end{function}
%
% \begin{function}{MK/AC,down-caption}
%  \begin{syntax}
%  |MK/AC| = \meta{string}\\
%  |down-caption| = \meta{string}
%  \end{syntax}
% This sets a text for the down-caption.
% \meta{string} is passed through \cs{pdf_string_from_unicode:nnN}
% and parentheses are added automatically. The key should be used only with
% pushbuttons. It is unclear if is actually used by the PDF viewer, but the
% pushbuttons modules uses the argument also to setup the appearance.
% \end{function}
%
% The remaining key are like the two above useful for pushbuttons only.
% Currently no special syntax support
% is implemented. They will be handled if needed when the code for
% push buttons is developed and tested.
% \begin{function}{MK/I,MK/RI,MK/IX,MK/IF,MK/TP}
%  \begin{syntax}
%  |MK/*| = \meta{various}
%  \end{syntax}
% These keys adds the various entries in the \emph{dynamic appearance dictionary}.
% * should be one of  |I|, |RI|, |IX|, |IF|, |TP|.
% The |MK| dictionary can also be added by using |\pdfannot_dict_put:nnn{Widget}{MK}{...}|
% but the two methods should not be mixed.
% \end{function}
%
% \end{documentation}
%
% \begin{implementation}
% \DoNotIndex
%  {
%   \\
% ,\bitset_clear:N
% ,\bitset_new:Nn
% ,\bitset_set_false:Nn
% ,\bitset_set_true:Nn
% ,\bitset_to_arabic:N
% ,\bool_new:N
% ,\clist_map_inline:nn
% ,\color_export:nnN
% ,\color_set:nn
% ,\color_set:nnn
% ,\cs_new_protected:Npn
% ,\cs_set_eq:NN
% ,\cs_set_protected:Npn
% ,\cs_if_exist:NTF
% ,\cs_if_exist:NT
% ,\cs_new:Npn
% ,\csname
% ,\dim_eval:n
% ,\dim_new:N
% ,\endcsname
% ,\exp_args:Ne
% ,\exp_args:Nnx
% ,\exp_args:NV
% ,\group_begin:
% ,\group_end:
% ,\hbox_to_wd:nn
% ,\hfill
% ,\hook_gput_code:nnn
% ,\int_eval:n
% ,\l_keys_choice_int
% ,\keys_define:nn
% ,\keys_set:nn
% ,\mode_leave_vertical:
% ,\msg_error:nnnn
% ,\msg_error:nnx
% ,\msg_new:nnn
% ,\msg_warning:nn
% ,\msg_warning:nnn
% ,\msg_info:nnn
% ,\msg_warning:nnnnn
% ,\NeedsTeXFormat
% ,\pdf_name_from_unicode_e:n
% ,\pdf_object_if_exist:nTF
% ,\pdf_object_new:nn
% ,\pdf_object_ref:n
% ,\pdf_object_ref_last:
% ,\pdf_object_unnamed_write:nx
% ,\pdf_object_write:nx
% ,\pdf_string_from_unicode:nnN
% ,\pdfannot_box_ref_last:
% ,\pdfannot_dict_put:nnn
% ,\pdfannot_dict_put:nnx
% ,\pdfannot_dict_remove:nn
% ,\pdfannot_widget_box:nnn
% ,\pdfdict_if_empty:nTF
% ,\pdfdict_if_empty:nF
% ,\pdfdict_new:n
% ,\pdfdict_put:nnn
% ,\pdfdict_put:nnx
% ,\pdfdict_remove:nn
% ,\pdfdict_use:n
% ,\pdfmanagement_add:nnn
% ,\pdfmanagement_add:nnx
% ,\pdfmeta_standard_verify:nTF
% ,\pdfmeta_standard_verify:nT
% ,\pdfmeta_standard_verify:nF
% ,\pdfxform_if_exist:nTF
% ,\pdfxform_new:nnn
% ,\pdfxform_ref:n
% ,\ProvidesExplPackage
% ,\rule
% ,\seq_gput_right:Nn
% ,\seq_gput_right:cx
% ,\seq_if_exist:NTF
% ,\seq_if_exist:cTF
% ,\seq_new:N
% ,\seq_new:c
% ,\seq_use:Nn
% ,\seq_use:cn
% ,\str_if_empty:NTF
% ,\str_if_in:NnTF
% ,\str_if_in:NnT
% ,\str_new:N
% ,\tl_if_empty:NTF
% ,\tl_if_empty:NF
% ,\tl_if_empty:nTF
% ,\tl_if_head_eq_charcode:nNTF
% ,\tl_new:N
% ,\tl_set:Nn
% ,\tl_to_str:n
%   }
% \section{\pkg{l3pdffield} Implementation}
%    \begin{macrocode}
%<*package>
%<@@=pdffield>
\NeedsTeXFormat{LaTeX2e}
\ProvidesExplPackage{l3pdffield-testphase}{2022-03-17}{0.95m}%
  {form fields}
%    \end{macrocode}
% \subsection{hyperref specific command}
% hyperref sets NeedAppearances by default. As this is deprecated we disable this.
%    \begin{macrocode}
\csname HyField@NeedAppearancesfalse\endcsname % suppress NeedAppearances
%    \end{macrocode}
%
% \subsection{local variables}
%
% \begin{variable}
%  {
%      \l_@@_tmpa_str
%     ,\l_@@_tmpb_str
%     ,\l_@@_tmpa_tl
%     ,\l_@@_tmpa_keys_tl
%     ,\l_@@_currentparent_tl
%     ,\l_@@_fieldID_tl
%     ,\l_@@_caption_tl
%     ,\l_@@_rollover_caption_tl
%     ,\l_@@_down_caption_tl
%     ,\g_@@_CO_sortkeys_prop
%     ,\l_@@_CO_sortkey_str
%     ,\g_@@_annot_ref_last_tl
%     ,\l_@@_tag_bool
%  }
% Some tmp variables, and a variable for the current parent and the
% current fieldID.
%    \begin{macrocode}
\str_new:N \l_@@_tmpa_str
\str_new:N \l_@@_tmpb_str
\tl_new:N  \l_@@_tmpa_tl
\tl_new:N  \l_@@_tmpa_keys_tl
\tl_new:N  \l_@@_currentparent_tl
\tl_new:N  \l_@@_fieldID_tl
\tl_new:N  \l_@@_caption_tl
\tl_new:N  \l_@@_rollover_caption_tl
\tl_new:N  \l_@@_down_caption_tl
\prop_new:N \g_@@_CO_sortkeys_prop
\seq_new:N \g_@@_CO_sortkeys_seq
\str_new:N  \l_@@_CO_sortkey_str
\tl_new:N \g_@@_annot_ref_last_tl
\bool_new:N \l_@@_tag_bool
\bool_set_true:N \l_@@_tag_bool
%    \end{macrocode}
% \end{variable}
%
%    \begin{macrocode}
\cs_new_protected:Npn \@@_tmpa:n #1 {}
\cs_new_protected:Npn \@@_tmpa:nn #1 #2 {}
%    \end{macrocode}

% \subsection{messages}
%    \begin{macrocode}
\msg_new:nnn {pdffield}{no-period}
  {
    The~field~name~`#1`~contains~a~period. \\
    This~is~not~allowed. `
  }
\msg_new:nnn {pdffield}{empty-name}
  {
    The~field~name~is~empty. \\
    This~is~not~allowed. `
  }
\msg_new:nnn {pdffield}{appearance-missing}
  {
    The~appearance~definition~`#1`~is~missing~for~the~#2~appearance.
  }
\msg_new:nnn {pdffield}{not-implemented}
  {
    Support~for~'/#1'~is~not~implemented\\
    The~key~is~ignored.
  }
\msg_new:nnn {pdffield}{key-disabled}
  {
    key~`#2`~is~disabled~and~ignored~in~the~`#1`~command.\\
    Use~key~`#3`~instead.
  }
\msg_new:nnn {pdffield}{parent-field-missing}
  {
    The~parent~field~'#1'~doesn't~exist\\
    Create~it~with~\tl_to_str:n{\pdffield_field:nn}
  }
\msg_new:nnn {pdffield}{key-ignored}
  {
    key~`#1`~has~no~function~and~is~ignored
  }
%    \end{macrocode}

% An auxiliary command to disable some keys
% \begin{macro}{\@@_key_disable:nnn}
%    \begin{macrocode}
\cs_new_protected:Npn \@@_key_disable:nnn #1#2#3
 {
   \keys_define:nn {pdffield}
    {
      #2 .code:n =
       {
         \msg_warning:nnnnn {pdffield}{key-disabled}{#1}{#2}{#3}
       }
    }
 }
%    \end{macrocode}
% \end{macro}
% \subsection{bitsets}
% \begin{macro}{\l_@@_Ff_bitset,\l_@@_F_bitset}
% The field and the annot bitset.
%    \begin{macrocode}
\bitset_new:Nn \l_@@_Ff_bitset
 {
    ReadOnly          = 1,
    Required          = 2,
    NoExport          = 3,
    Multiline         = 13,%Tx
    Password          = 14,
    NoToggleToOff     = 15,%Btn, radio button
    Radio             = 16,%Btn: Radio:    15=1, 16=0
    Pushbutton        = 17,%Btn: Checkbox: 15=0, 16=0
                           %Btn: Pushbutton: 16=1
    Combo             = 18,%Ch: Combo=1 List=0
    Edit              = 19,%Ch, Combo=1 -> + edit field
    Sort              = 20,%Ch, not relevant for view...
    FileSelect        = 21,%Tx
    MultiSelect       = 22,%Ch
    DoNotSpellCheck   = 23,%Tx, Ch (if Combo + Edit set)
    DoNotScroll       = 24,%Tx
    Comb              = 25,%Tx, requires MaxLen in dict
    RadiosInUnison    = 26,%Btn Radio
    RichText          = 26,%Tx
    CommitOnSelChange = 27,
    readonly          = 1,
    required          = 2,
    noexport          = 3,
    multiline         = 13,%Tx
    password          = 14,
    notoggletooff     = 15,%Btn, radio button
    radio             = 16,%Btn: Radio:    15=1, 16=0
    pushbutton        = 17,%Btn: Checkbox: 15=0, 16=0
                           %Btn: Pushbutton: 16=1
    combo             = 18,%Ch: Combo=1 List=0
    edit              = 19,%Ch, Combo=1 -> + edit field
    sort              = 20,%Ch, not relevant for view...
    fileselect        = 21,%Tx
    multiselect       = 22,%Ch
    donotspellcheck   = 23,%Tx, Ch (if Combo + Edit set)
    donotscroll       = 24,%Tx
    comb              = 25,%Tx, requires MaxLen in dict
    radiosinunison    = 26,%Btn Radio
    richtext          = 26,%Tx
    commitonselchange = 27
  }

\bitset_new:Nn \l_@@_F_bitset
  {
    Invisible      = 1,
    Hidden         = 2,
    Print          = 3,
    NoZoom         = 4,
    NoRotate       = 5,
    NoView         = 6,
    ReadOnly       = 7,
    Locked         = 8,
    ToggleNoView   = 9,
    LockedContents = 10,
    invisible      = 1,
    hidden         = 2,
    print          = 3,
    nozoom         = 4,
    norotate       = 5,
    noview         = 6,
    readonly       = 7,
    locked         = 8,
    togglenoview   = 9,
    lockedcontents = 10
  }
%    \end{macrocode}
% \end{macro}
% \subsection{The field dictionary}
% The field dictionary is the main object.
% To be able to set values from the outside it will use a
% dictionary which can be filled by key-val.
%    \begin{macrocode}
\pdfdict_new:n   {l_@@/field}
\pdfdict_new:n   {l_@@/field/AA}
%    \end{macrocode}
% \begin{macro}{\@@_field:n,\pdffield_field:nn}
% \begin{syntax}
% \cs{@@_field:n}\Arg{field ID}
% \end{syntax}
%    \begin{macrocode}
\cs_new_protected:Npn \@@_field:n #1
  {
    \pdf_object_new:nn {@@/field/#1}      {dict}
    \pdf_object_new:nn {@@/field/Kids/#1} {array}
    \tl_if_empty:NTF \l_@@_currentparent_tl
      {
        \pdfmanagement_add:nnx
          { Catalog / AcroForm }
          { Fields }
          {\pdf_object_ref:n {@@/field/#1} }
      }
      {
        \exp_args:Ne
        \pdf_object_if_exist:nTF {@@/field/\l_@@_currentparent_tl}
          {
            \pdfdict_put:nnx { l_@@/field }{Parent}
              {\exp_args:Ne \pdf_object_ref:n{@@/field/\l_@@_currentparent_tl}}
            \seq_gput_right:cx {g_@@_field/Kids/\l_@@_currentparent_tl _seq}
              { \exp_args:Ne \pdf_object_ref:n{@@/field/#1}}
          }
          {
            \msg_error:nnx {pdffield}{parent-field-missing}{\l_@@_currentparent_tl}
          }
      }
    \seq_new:c {g_@@_field/Kids/#1_seq}
    \pdfdict_put:nnx {l_@@/field}
      {Kids}
      {
        \pdf_object_ref:n {@@/field/Kids/#1}
      }
    \pdfdict_put:nnx {l_@@/field}
      {Ff}
      {\bitset_to_arabic:N \l_@@_Ff_bitset }
    \pdfdict_if_empty:nF{l_@@/field/AA}
      {
        \pdfmeta_standard_verify:nT
          {annot_widget_no_AA}
          {
            \pdf_object_unnamed_write:nx {dict}{\pdfdict_use:n {l_@@/field/AA}}
            \pdfdict_put:nnx
              {l_@@/field}
              {AA}
              {\pdf_object_ref_last:}
            \pdfdict_get:nnN {l_@@/field/AA}{C}\l_@@_tmpa_tl
            \quark_if_no_value:NF \l_@@_tmpa_tl
              {
                \prop_gput:Nxx\g_@@_CO_sortkeys_prop
                  { \pdf_object_ref:n {@@/field/#1} }{ \l_@@_CO_sortkey_str }
                \seq_gput_right:Nx\g_@@_CO_sortkeys_seq
                  { \pdf_object_ref:n {@@/field/#1} }
              }
          }
      }
    \hook_gput_code:nnn {shipout/lastpage}{pdffield} %xetex needs this ...
      {
        \pdf_object_write:nx {@@/field/Kids/#1}
          {
            \seq_use:cn{g_@@_field/Kids/#1_seq}{~}
          }
      }
    \pdf_object_write:nx {@@/field/#1} { \pdfdict_use:n {l_@@/field} }
  }

\hook_gput_code:nnn {shipout/lastpage}{pdffield}
  {
     \prop_if_empty:NF \g_@@_CO_sortkeys_prop
       {
          \seq_sort:Nn \g_@@_CO_sortkeys_seq
           {
              \str_compare:eNeTF
                { \prop_item:Nn \g_@@_CO_sortkeys_prop {#1} }
                >
                { \prop_item:Nn \g_@@_CO_sortkeys_prop {#2} }
                { \sort_return_swapped: }
                { \sort_return_same: }
           }
           \pdfmanagement_add:nnx
            { Catalog / AcroForm }
            { CO }
            { \seq_use:Nn \g_@@_CO_sortkeys_seq{~} }
       }
   }

\cs_new_protected:Npn \pdffield_field:nn #1 #2
  {
    \group_begin:
    \keys_set:nn { pdffield } {#1}
    \@@_field:n {#2}
    \group_end:
  }
%    \end{macrocode}
% \end{macro}
%
% \subsection{The annot dictionary}
% We assume that the annotation should really occupy space on the page and
% leave vertical mode.
%
% \begin{macro}{\@@_annot:,\pdffield_annot:n}
% The command doesn't add grouping, so should only be used inside a group.
%
%    \begin{macrocode}
\cs_new_protected:Npn \@@_annot:
  {
    \pdfmeta_standard_verify:nF
      {annot_flags}
      {
        \bitset_set_true:Nn  \l_@@_F_bitset {Print}
        \bitset_set_false:Nn \l_@@_F_bitset {Hidden}
        \bitset_set_false:Nn \l_@@_F_bitset {Invisible}
        \bitset_set_false:Nn \l_@@_F_bitset {NoView}
      }
    \pdfannot_dict_put:nnx {widget}{F}{ \bitset_to_arabic:N \l_@@_F_bitset }
    \@@_tag_add_struct_parent:
    \tl_if_empty:NF \l_@@_currentparent_tl
      {
         \exp_args:Ne
         \pdf_object_if_exist:nTF { @@/field/\l_@@_currentparent_tl }
           {
             \pdfannot_dict_put:nnx {widget}{Parent}
               {
                 \exp_args:Ne
                   \pdf_object_ref:n{@@/field/\l_@@_currentparent_tl}
               }
           }
           {
               \msg_error:nnx { pdffield }{parent-field-missing}{\l_@@_currentparent_tl}
           }
       }
    \mode_leave_vertical:
    \@@_tag_struct_begin:
    \hbox_to_wd:nn
      { \l_@@_annot_wd_dim  }
      {
        \rule [-\l_@@_annot_dp_dim]{0pt}{\dim_eval:n{\l_@@_annot_ht_dim+\l_@@_annot_dp_dim} }
        \pdfannot_widget_box:nnn
           { \l_@@_annot_wd_dim }
           { \l_@@_annot_ht_dim }
           { \l_@@_annot_dp_dim }
         \hfill
      }
    \tl_gset:Nx \g_@@_annot_ref_last_tl { \pdfannot_box_ref_last: }
    \exp_args:NV \@@_tag_add_objr:n \g_@@_annot_ref_last_tl
    \@@_tag_struct_end:
    \tl_if_empty:NF \l_@@_currentparent_tl
      {
        \seq_if_exist:cTF {g_@@_field/Kids/\l_@@_currentparent_tl _seq}
         {
           \seq_gput_right:cx
             {g_@@_field/Kids/\l_@@_currentparent_tl _seq}
             { \g_@@_annot_ref_last_tl }
         }
         {
           \msg_error:nnx { pdffield}{parent-field-missing}{\l_@@_currentparent_tl}
         }
      }
  }
\cs_new_protected:Npn \pdffield_annot:n #1
  {
    \group_begin:
    \keys_set:nn { pdffield } {#1}
    \@@_annot:
    \group_end:
  }
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{\pdffield_annot_ref_last:}
%    \begin{macrocode}
\cs_new:Npn \pdffield_annot_ref_last: { \g_@@_annot_ref_last_tl }
%    \end{macrocode}
% \end{macro}
% \subsection{Tagging}
% \begin{macro}
%  {
%   \@@_tag_add_struct_parent:,
%   \@@_tag_add_objr:n,
%   \@@_tag_struct_begin:
%   \@@_tag_struct_end:
%   }
%    \begin{macrocode}
\cs_new_protected:Npn \@@_tag_add_struct_parent: {}
\cs_new_protected:Npn \@@_tag_add_objr:n #1 {}
\cs_new_protected:Npn \@@_tag_struct_begin: {}
\cs_new_protected:Npn \@@_tag_struct_end: {}
\hook_gput_code:nnn {begindocument} { l3pdffield }
 {
   \cs_if_exist:NT \tag_if_active:T
    {
      \tag_if_active:T
       {
         \cs_set_protected:Npn \@@_tag_add_struct_parent:
           {
             \bool_if:NT \l_@@_tag_bool
              {
                \pdfannot_dict_put:nnx {widget}{StructParent}{ \tag_struct_parent_int: }
              }
           }
         \cs_set_protected:Npn \@@_tag_add_objr:n #1
           {
             \bool_if:NT \l_@@_tag_bool
               {
                 \exp_args:Nnx
                 \tag_struct_insert_annot:nn {#1}{ \tag_struct_parent_int: }
               }
           }
         \cs_set_protected:Npn \@@_tag_struct_begin:
          {
            \bool_if:NT \l_@@_tag_bool
             {
                \tag_mc_end_push:
                \tag_struct_begin:n{tag=Form}
             }
          }
         \cs_set_protected:Npn \@@_tag_struct_end:
          {
            \bool_if:NT \l_@@_tag_bool
             {
               \tag_struct_end:
               \tag_mc_begin_pop:n{}
             }
          }
       }
    }
 }
%    \end{macrocode}
% \end{macro}
% \subsection{auxiliary command for color keys}
% \begin{macro}{\@@_color_set:nn }
%    \begin{macrocode}
\cs_new_protected:Npn \@@_color_set:nn #1 #2
 {
   \tl_if_head_eq_charcode:nNTF {#2}[ %]
    {
      \@@_color_set_aux:nwn  { #1 } #2
    }
    {
      \color_set:nn {#1} {#2}
    }
 }

\cs_new_protected:Npn \@@_color_set_aux:nwn #1 [#2] #3
  {
     \color_set:nnn {#1}{#2}{#3}
  }

%    \end{macrocode}
% \end{macro}
% \subsection{Field keys}
% The names. The main name should not be empty, it is added to the dictionary
% when the field is created. A new name means a new field.
% The other names can only be set when the field is created,
% so we put them in the field group.
%  \begin{macro}{\@@_V_handler:nN}
%  Values (V and DV) need different handling in the various field types. So
%  it uses a handler which can be redefined locally. By default it simply stores
%  the value in a tl var.
%    \begin{macrocode}
\cs_new_protected:Npn \@@_V_handler:nN #1#2
  {
    \tl_set:Nn #2 {#1}
  }
%    \end{macrocode}
% \end{macro}
% \begin{macro}{parent,T,name,TU,altname,TM,mappingname}
%    \begin{macrocode}
\keys_define:nn { pdffield  }
  {
    ,parent .tl_set:N = \l_@@_currentparent_tl
    ,parent .groups:n = {field,annot}
    ,T .code:n =
      {
        \pdf_string_from_unicode:nnN {utf8/string-raw}{#1}\l_@@_tmpa_str
        \str_if_in:NnT \l_@@_tmpa_str {.}
          {
            \msg_error:nnx {pdffield}{no-period}{\l_@@_tmpa_str}
          }
        \str_if_empty:NTF\l_@@_tmpa_str
          {
            \msg_warning:nn {pdffield}{empty-name}
            \pdfdict_remove:nn { l_@@/field }{T}
          }
          {
            \pdfdict_put:nnx { l_@@/field }{T}{(\l_@@_tmpa_str)}
          }
      }
    ,T .value_required:n = true
    ,T .groups:n = {field}
    ,name .meta:n          = {T={#1}}
    ,name .value_required:n = true
    ,name .groups:n = {field}
    ,TU .groups:n = {field}
    ,TU .code:n =
      {
        \tl_if_empty:nTF {#1}
          {
            \pdfdict_remove:nn { l_@@/field }{TU}
          }
          {
            \pdf_string_from_unicode:nnN {utf16/hex}{#1}\l_@@_tmpa_str
            \pdfdict_put:nnx { l_@@/field }{TU}{\l_@@_tmpa_str}
          }
      }
    ,TU .groups:n = {field}
    ,altname .meta:n      = {TU={#1}}
    ,altname .groups:n = {field}
    ,TM .code:n =
      {
        \tl_if_empty:nTF {#1}
          {
            \pdfdict_remove:nn { l_@@/field }{TM}
          }
          {
            \pdf_string_from_unicode:nnN {utf16/hex}{#1}\l_@@_tmpa_str
            \pdfdict_put:nnx { l_@@/field }{TM}{\l_@@_tmpa_str}
          }
      }
    ,TM .groups:n = {field}
    ,mappingname .meta:n   = {TM={#1}}
    ,mappingname .groups:n = {field}
    }
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{fieldID}
% For some field types we need a fieldID.
%
%    \begin{macrocode}
\keys_define:nn { pdffield }
 {
   fieldID .tl_set:N = \l_@@_fieldID_tl
 }
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{FT,V,DV,MaxLen,Lock,SV,Opt,TI,I}
%    \begin{macrocode}
\keys_define:nn{pdffield}
  {
    ,FT .choices:nn =
      { Btn, Tx, Ch, Sig }
      {
        \pdfdict_put:nnn { l_@@/field }{FT}{ /#1 }
      }
    ,FT .groups:n = {field}
    ,V .code:n =
     {
       \tl_if_empty:nTF {#1}
         {
           \pdfdict_remove:nn { l_@@/field }{V}
         }
         {
           \@@_V_handler:nN{#1}\l_@@_tmpa_str
           \pdfdict_put:nnx { l_@@/field }{V}{ \l_@@_tmpa_str }
         }
     }
    ,V .groups:n = {field}
    ,DV .code:n =
     {
       \tl_if_empty:nTF {#1}
         {
           \pdfdict_remove:nn { l_@@/field }{DV}
         }
         {
           \@@_V_handler:nN{#1}\l_@@_tmpa_str
           \pdfdict_put:nnx { l_@@/field }{DV}{ \l_@@_tmpa_str }
         }
     }
    ,DV .groups:n = {field}
    ,MaxLen .code:n =
     {
       \tl_if_empty:nTF {#1}
         {
           \pdfdict_remove:nn { l_@@/field }{MaxLen}
         }
         {
           \pdfdict_put:nnx { l_@@/field }{MaxLen}{ #1 }
         }
      }
    ,MaxLen .groups:n = {field}
    ,Lock .code:n =
      {
        \tl_if_empty:nTF {#1}
          {
            \pdfdict_remove:nn { l_@@/field }{Lock}
          }
          {
            \pdfdict_put:nnx { l_@@/field }{Lock}{ \pdf_object_ref:n{#1} }
          }
      }
    ,Lock .groups:n = {field}
    ,SV .code:n =
      {
        \tl_if_empty:nTF {#1}
          {
            \pdfdict_remove:nn { l_@@/field }{SV}
          }
          {
            \pdfdict_put:nnx { l_@@/field }{SV}{ \pdf_object_ref:n{#1} }
          }
      }
    ,SV .groups:n = {field}
    ,Opt .code:n =
      {
        \tl_if_empty:nTF {#1}
          {
            \pdfdict_remove:nn { l_@@/field }{Opt}
          }
          {
            \pdfdict_put:nnx { l_@@/field }{Opt}{ \pdf_object_ref:n{#1} }
          }
      }
    ,Opt .groups:n = {field}
    ,TI .code:n =
      {
        \tl_if_empty:nTF {#1}
          {
            \pdfdict_remove:nn { l_@@/field }{TI}
          }
          {
            \pdfdict_put:nnx { l_@@/field }{TI}{ #1 }
          }
       }
    ,TI .groups:n = {field}
    ,I .code:n =
      {
        \tl_if_empty:nTF {#1}
          {
            \pdfdict_remove:nn { l_@@/field }{I}
          }
          {
            \pdfdict_put:nnx { l_@@/field }{I}{ \pdf_object_ref:n{#1} }
          }
      }
    ,I .groups:n = {field}
  }
%    \end{macrocode}
% \end{macro}
% Flags. We don't add lots of individual keys but map the key names directly
% \begin{macro}{setFf,setfieldflags,unsetFf,unsetfieldflags}
%    \begin{macrocode}
\keys_define:nn { pdffield }
  {
    ,setFf .code:n =
      {
          \clist_map_inline:nn {#1}
           {
             \bitset_set_true:Nn \l_@@_Ff_bitset {##1}
           }
      }
    ,setFf .groups:n = {field}
    ,setfieldflags .meta:n =
      {setFf={#1}}
    ,setfieldflags .groups:n = {field}
    ,unsetFf .multichoice:
    ,unsetFf / all .code:n = { \bitset_clear:N \l_@@_Ff_bitset}
    ,unsetFf / unknown .code:n =
      {
        \bitset_set_false:Nn \l_@@_Ff_bitset {#1}
      }
    ,unsetFf .groups:n = {field}
    ,unsetfieldflags .meta:n = {unsetFf={#1}}
    ,unsetfieldflags .groups:n = {field}
  }

%    \end{macrocode}
% \end{macro}
% \begin{macro}
%  {
%    AA/K,keystroke,AA/F,format,
%    AA/V,validate,AA/C,calculate
%  }
%  Keys for the AA dictionary. They all trigger a javascript option.
%  K=keystroke, F=format, V=validate, C=calculate
%    \begin{macrocode}
\cs_set_protected:Npn \@@_tmpa:n #1  %
  {
    \keys_define:nn { pdffield  }
      {
         AA/#1 .code:n =
           {
             \tl_if_empty:nTF {#1}
               {
                 \pdfdict_remove:nn {l_@@/field/AA}{#1}
               }
               {
                 \pdfdict_put:nnx {l_@@/field/AA}
                  {#1}
                  {<</S/JavaScript/JS\c_space_tl ##1>>}
               }
           },
        AA/#1 .groups:n  = {field}
      }
  }

\clist_map_inline:nn {K,F,V,C}{\@@_tmpa:n{#1}}

\cs_set_protected:Npn \@@_tmpa:nn #1 #2
  {
    \keys_define:nn { pdffield  }
      {
         #1 .meta:nn =
           { pdffield }{AA/#2={##1}},
        #1 .groups:n  = {field}
      }
  }
\@@_tmpa:nn {keystroke}{K}
\@@_tmpa:nn {format}   {F}
\@@_tmpa:nn {validate} {V}
\@@_tmpa:nn {calculate}{C}

\keys_define:nn {pdffield}
 {
   sortkey .code:n = {\str_set:Nx \l_@@_CO_sortkey_str {\tl_to_str:n{#1}}}
 }
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{DA,Q,align,DS,RV}
% The following keys are related to textfield and their format.
%    \begin{macrocode}
\keys_define:nn { pdffield }
  {
    DA .code:n =
     {
       \tl_if_empty:nTF {#1}
         {
           \pdfdict_remove:nn { l_@@/field }{DA}
         }
         {
           \pdfdict_put:nnx { l_@@/field }{DA}{ (#1) }
         }
      }
    ,DA .groups:n = {field}
    ,Q .choices:nn = {left,center,right}
     {
       \pdfdict_put:nnx { l_@@/field }{Q}{ \int_eval:n{\l_keys_choice_int-1} }
     }
    ,Q / .code:n = { \pdfdict_remove:nn { l_@@/field }{Q} }
    ,Q .groups:n = {field}
    ,align .meta:n={Q=#1}
    ,DS .code:n =
     {
       \msg_warning:nnn {pdffield}{not-implemented}{DS}
     }
    ,DS .groups:n = {field}
    ,RV .code:n =
     {
       \msg_warning:nnn {pdffield}{not-implemented}{RV}
     }
    ,RV .groups:n = {field}
  }
%    \end{macrocode}
% \end{macro}
% \subsection{Annotation keys}
% The size of the field annotation
% \begin{variable}
%  {
%    \l_@@_annot_ht_dim,
%    \l_@@_annot_wd_dim,
%    \l_@@_annot_dp_dim
%  }
%    \begin{macrocode}
\dim_new:N \l_@@_annot_ht_dim
\dim_new:N \l_@@_annot_wd_dim
\dim_new:N \l_@@_annot_dp_dim
%    \end{macrocode}
% \end{variable}
% \begin{macro}{width,height,depth}
% The size of the field annotation.
%    \begin{macrocode}
\keys_define:nn { pdffield }
  {
    ,width  .dim_set:N = \l_@@_annot_wd_dim
    ,height .dim_set:N = \l_@@_annot_ht_dim
    ,depth  .dim_set:N = \l_@@_annot_dp_dim
    ,width  .initial:n = 0pt
    ,height .initial:n = 0pt
    ,depth  .initial:n = 0pt
  }
%    \end{macrocode}
% \end{macro}
% \begin{macro}{tag}
% to disable tagging locally
%    \begin{macrocode}
\keys_define:nn { pdffield }
  {
    ,tag  .bool_set:N = \l_@@_tag_bool
  }
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\@@_appearance_handler:nnn}
% Appearances have to be handled in various ways, so we use a handler, that
% the field types can redefine if needed.
%    \begin{macrocode}
\cs_new_protected:Npn \@@_appearance_handler:nnn #1#2#3
 {
   \pdfxform_if_exist:nTF {  #1 }
     {
       \pdfannot_dict_put:nnx {widget/AP}{#2}
         {
           \pdfxform_ref:n {#1}
         }
     }
     {
       \msg_error:nnnn{pdffield}{appearance-missing}{#1}{#3}
     }
 }
%    \end{macrocode}
% \end{macro}
% \begin{macro}{AS,AP/N,appearance,AP/R,rollover-appearance,AP/D,down-appearance}
% The key for the default appearance and the various types.
%    \begin{macrocode}
\keys_define:nn { pdffield }
 {
   %parent is defined in field
  ,AS .code:n =
    {
      \tl_if_empty:nTF {#1}
        {
          \pdfannot_dict_remove:nn { widget }{AS}
        }
        {
          \pdfannot_dict_put:nnx {widget}{AS}{\pdf_name_from_unicode_e:n{#1}}
        }
    }
  ,AS .groups:n = annot
 }
\keys_define:nn { pdffield }
  {
    AP/N .code:n =
      {
        \tl_if_empty:nTF {#1}
          {
            \pdfannot_dict_remove:nn { widget/AP }{N}
          }
          {
            \@@_appearance_handler:nnn {#1}{N}{normal}
          }
        }
   ,AP/N .groups:n = annot
   ,appearance .meta:n = {AP/N={#1}}
   ,appearance .groups:n = annot
  }
\keys_define:nn { pdffield }
  {
    AP/R .code:n =
      {
        \tl_if_empty:nTF {#1}
          {
            \pdfannot_dict_remove:nn { widget/AP }{R}
          }
          {
             \@@_appearance_handler:nnn {#1}{R}{rollover}
          }
        }
   ,AP/R .groups:n = annot
   ,rollover-appearance .meta:n = {AP/R={#1}}
   ,rollover-appearance .groups:n = annot
  }
\keys_define:nn { pdffield }
  {
    AP/D .code:n =
      {
        \tl_if_empty:nTF {#1}
          {
            \pdfannot_dict_remove:nn { widget/AP }{D}
          }
          {
             \@@_appearance_handler:nnn {#1}{D}{down}
          }
        }
   ,AP/D .groups:n = annot
   ,down-appearance .meta:n = {AP/D={#1}}
   ,down-appearance .groups:n = annot
  }
%    \end{macrocode}
% \end{macro}
% \begin{macro}{MK/R,rotate,MK/BC,bordercolor,MK/BG,backgroundcolor,MK/CA,caption}
% This are the keys for the dynamic appearance. A number are not handled yet fully.
%    \begin{macrocode}
\keys_define:nn { pdffield  }
  {
    MK/R .choices:nn = {0,90,180,270}
     {
       \pdfannot_dict_put:nnx {widget/MK}{R}{#1}
     }
   ,MK/R / .code:n =
     {
        \pdfannot_dict_remove:nn { widget/MK }{R}
     }
   ,MK/R .groups:n = annot
   ,rotate .meta:n = {MK/R=#1}
  }

\keys_define:nn { pdffield  }
  {
    MK/BC .code:n =
     {
       \tl_if_empty:nTF {#1}
        {
          \pdfannot_dict_remove:nn { widget/MK }{BC}
        }
        {
          \@@_color_set:nn {@@/tmp}{#1}
          \color_export:nnN{@@/tmp}{space-sep-rgb}\l_@@_tmpa_tl
          \pdfannot_dict_put:nnx {widget/MK}{BC}{[\l_@@_tmpa_tl]}
        }
     }
    ,MK/BC .groups:n = annot
   ,bordercolor .meta:n = {MK/BC=#1}
  }

\keys_define:nn { pdffield  }
  {
    MK/BG .code:n =
     {
       \tl_if_empty:nTF {#1}
        {
          \pdfannot_dict_remove:nn { widget/MK }{BG}
        }
        {
          \@@_color_set:nn {@@/tmp}{#1}
          \color_export:nnN{@@/tmp}{space-sep-rgb}\l_@@_tmpa_tl
          \pdfannot_dict_put:nnx {widget/MK}{BG}{[\l_@@_tmpa_tl]}
        }
     }
    ,MK/BG .groups:n = annot
   ,backgroundcolor .meta:n = {MK/BG=#1}
  }


\keys_define:nn { pdffield  }
  {
    MK/CA .code:n =
     {
       \tl_set:Nn \l_@@_caption_tl {#1}
       \tl_if_empty:nTF {#1}
        {
          \pdfannot_dict_remove:nn { widget/MK }{CA}
        }
        {
          \pdf_string_from_unicode:nnN {utf8/string}{#1}\l_@@_tmpa_str
          \pdfannot_dict_put:nnx {widget/MK}{CA}{\l_@@_tmpa_str}
        }
     }
    ,MK/CA .groups:n = annot
   ,caption .meta:n = {MK/CA=#1}
  }

\keys_define:nn { pdffield  }
  {
    MK/RC .code:n =
     {
       \tl_set:Nn \l_@@_rollover_caption_tl {#1}
       \tl_if_empty:nTF {#1}
        {
          \pdfannot_dict_remove:nn { widget/MK }{RC}
        }
        {
          \pdf_string_from_unicode:nnN {utf8/string}{#1}\l_@@_tmpa_str
          \pdfannot_dict_put:nnx {widget/MK}{RC}{\l_@@_tmpa_str}
        }
     }
    ,MK/RC .groups:n = annot
   ,rollover-caption .meta:n = {MK/RC=#1}
  }

\keys_define:nn { pdffield  }
  {
    MK/AC .code:n =
     {
       \tl_set:Nn \l_@@_down_caption_tl {#1}
       \tl_if_empty:nTF {#1}
        {
          \pdfannot_dict_remove:nn { widget/MK }{AC}
        }
        {
          \pdf_string_from_unicode:nnN {utf8/string}{#1}\l_@@_tmpa_str
          \pdfannot_dict_put:nnx {widget/MK}{AC}{\l_@@_tmpa_str}
        }
     }
    ,MK/AC .groups:n = annot
   ,down-caption .meta:n = {MK/AC=#1}
  }
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{MK/I,MK/RI,MK/IX,MK/IF,MK/TP}
% The following keys are pushputtons only. Currently there is no special handling
% involved as it is unclear if they are useful.
%    \begin{macrocode}

\cs_set_protected:Npn \@@_tmpa:n #1
 {
   \keys_define:nn { pdffield  }
     {
       MK/#1 .code:n =
        {
          \tl_if_empty:nTF {##1}
            {
              \pdfannot_dict_remove:nn { widget/MK }{#1}
            }
            {
              \pdfannot_dict_put:nnx {widget/MK}{#1}{##1}
            }
        }
      ,MK/#1 .groups:n = annot
     }
 }

\clist_map_inline:nn {I,RI,IX,IF,TP}
  { \@@_tmpa:n {#1} }
%    \end{macrocode}
% \end{macro}
%
% Flags.
%  \begin{macro}{setF,setannotflags,unsetF,unsetannotflags}
%    \begin{macrocode}
\keys_define:nn { pdffield  }
  {
    ,setF .code:n =
      {
          \clist_map_inline:nn {#1}
           {
             \bitset_set_true:Nn \l_@@_F_bitset {##1}
           }
      }
    ,setF .groups:n = annot
    ,setannotflags .meta:nn =
      { pdffield }{setF={#1}}
    ,setannotflags .groups:n = annot
    ,unsetF .multichoice:
    ,unsetF / all .code:n = { \bitset_clear:N \l_@@_F_bitset}
    ,unsetF / unknown .code:n =
      {
        \bitset_set_false:Nn \l_@@_F_bitset {#1}
      }
    ,unsetF .groups:n = annot
    ,unsetannotflags .meta:nn =
      { pdffield }{unsetF= {#1} }
    ,unsetannotflags .groups:n = annot
  }

%    \end{macrocode}
% \end{macro}
% Keys for the AA dictionary. They all trigger a javascript option.
% Fo = onfocus, Bl = onblur, D = onmousedown, U = onmouseup,
% E = onenter, X = onexit, PO = pageopen, PC = pageclose,
% PV = pagevisible, PI = pageinvisible
% \begin{macro}
%  {
%    AA/Fo,onfocus, AA/Bl,onblur, AA/D,onmousedown, AA/U,onmouseup,
%    AA/E,onenter, AA/X,onexit, AA/PO,pageopen, AA/PC,pageclose,
%    AA/PV,pagevisible, AA/PI,pageinvisible
%  }
%    \begin{macrocode}
\cs_set_protected:Npn \@@_tmpa:n #1  %
  {
    \keys_define:nn { pdffield }
      {
         AA/#1 .code:n =
           {
             \tl_if_empty:nTF {#1}
               {
                 \pdfannot_dict_remove:nn {widget/AA}{#1}
               }
               {
                 \pdfannot_dict_put:nnx {widget/AA}
                  {#1}
                  {<</S/JavaScript/JS\c_space_tl##1>>}
               }
           },
         ,AA/#1 .groups:n = annot
      }
  }

\clist_map_inline:nn {Fo,Bl,D,U,E,X,PO,PC,PV,PI}{\@@_tmpa:n{#1}}

\cs_set_protected:Npn \@@_tmpa:nn #1 #2
  {
    \keys_define:nn { pdffield }
      {
         #1 .meta:nn =
           { pdffield }{AA/#2={##1}},
         #1 .groups:n = {annot}
      }
  }
\@@_tmpa:nn {onfocus}  {Fo}
\@@_tmpa:nn {onblur}   {Bl}
\@@_tmpa:nn {onmousedown}{D}
\@@_tmpa:nn {onmouseup}{U}
\@@_tmpa:nn {onenter}  {E}
\@@_tmpa:nn {onexit}   {X}
%    \end{macrocode}
% \end{macro}
% \subsection{Appearances}
% \begin{macro}{\pdffield_appearance:nn,\pdffield_store_appearance:nn}
%    \begin{macrocode}
\cs_new_protected:Npn \pdffield_appearance:nn #1 #2
  {
     \pdfxform_new:nnn {#1}{}{#2}
  }

\cs_set_eq:NN \pdffield_store_appearance:nn\pdffield_appearance:nn
%    \end{macrocode}
% \end{macro}
% \subsection{Setup command}
% \begin{macro}{create-style,preset-checkbox,preset-radio,preset-textfield}
%    \begin{macrocode}
\keys_define:nn { pdffield / setup }
  {
    ,create-style .code:n  = { \@@_style_create:nn #1 }
    ,preset-checkbox .code:n =
      {
        \keys_define:nn { pdffield }
         {
           @@/preset/checkbox .meta:n = {#1},
         }
      }
    ,preset-radiobutton .code:n =
      {
        \keys_define:nn { pdffield }
         {
           @@/preset/radiobutton .meta:n = {#1},
         }
      }
   ,preset-textfield .code:n =
      {
        \keys_define:nn { pdffield }
         {
           @@/preset/textfield .meta:n = {#1},
         }
      }
   ,preset-pushbutton .code:n =
      {
        \keys_define:nn { pdffield }
         {
           @@/preset/pushbutton .meta:n = {#1},
         }
      }
  ,preset-choice .code:n =
      {
        \keys_define:nn { pdffield }
         {
           @@/preset/choice .meta:n = {#1},
         }
      }
  }
\keys_set:nn{ pdffield / setup }{preset-checkbox={}}
\keys_set:nn{ pdffield / setup }{preset-textfield={}}
\keys_set:nn{ pdffield / setup }{preset-radiobutton={}}
\keys_set:nn{ pdffield / setup }{preset-pushbutton={}}
\keys_set:nn{ pdffield / setup }{preset-choice={}}
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\@@_style_create:nn}
%    \begin{macrocode}
\cs_new_protected:Npn \@@_style_create:nn #1#2
  {
    \keys_define:nn { pdffield }
      {
        @@/style/#1 .meta:n = {#2},
      }
  }

%    \end{macrocode}
% \end{macro}
% \begin{macro}{\pdffield_setup:n,style}
%    \begin{macrocode}
\cs_new_protected:Npn \pdffield_setup:n #1
  {
     \keys_set:nn{ pdffield / setup }{#1}
  }

\keys_define:nn { pdffield }
  {
    style .code:n = {\keys_set:nn {pdffield}{@@/style/#1={#1}}}
  }
%    \end{macrocode}
% \end{macro}
% \section{Value keys}
% \begin{macro}{value,default,\@@_value_handler:n,\@@_default_handler:n}
%    \begin{macrocode}
\cs_new_protected:Npn \@@_value_handler:n #1
  {
    \msg_info:nnn {pdffield}{key-ignored}{value}
  }
\cs_new_protected:Npn \@@_default_handler:n #1
  {
    \msg_info:nnn {pdffield}{key-ignored}{default}
  }
\keys_define:nn {pdffield}
  {
     value   .code:n = { \@@_value_handler:n {#1} }
    ,default .code:n = { \@@_default_handler:n {#1}}
  }
%    \end{macrocode}
% \end{macro}
%    \begin{macrocode}
%</package>
%    \end{macrocode}
%\end{implementation}
%
% \PrintIndex