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+texdimens
+=========
+
+## Copyright and License
+
+Copyright (c) 2021 Jean-François Burnol
+
+This file is part of the texdimens package distributed under the
+LPPL 1.3c. See file LICENSE.md.
+
+Repository: https://github.com/jfbu/texdimens
+
+Release: `0.99d 2021/11/04`
+
+## Usage
+
+Utilities and documentation related to TeX dimensional units, usable:
+
+- with Plain TeX: `\input texdimens`
+
+- with LaTeX: `\usepackage{texdimens}`
+
+## Aim of this package
+
+The aim of this package is to provide facilities to express dimensions
+(or dimension expressions evaluated by `\dimexpr`) using the various
+available TeX units, to the extent possible.
+
+## Macros of this package (summary)
+
+This package provides expandable macros:
+
+- `\texdimenpt`,
+- `\texdimenUU`, `\texdimenUUup` and
+ `\texdimenUUdown` with `UU` standing for one of `bp`, `cm`, `mm`, `in`,
+ `pc`, `cc`, `nc`, `dd` and `nd`,
+- `\texdimenbothincm` (and relatives not listed here, see below),
+- `\texdimenwithunit`.
+
+For example `\texdimenbp` takes on input some dimension or dimension
+expression and produces on output a decimal `D` such that `D bp` is
+guaranteed to be the same dimension as the input, if that one admits any
+representation as `E bp`; else it will be either the closest match from
+above or from below (for this unit the error is at most `1sp`).
+
+The variants `\texdimenbpup` and `\texdimenbpdown` allow to choose the
+direction of approximation.
+
+`\texdimenwithunit{<dimen1>}{<dimen2>}` produces a decimal `D` such that
+`D \dimexpr dimen2\relax` is parsed by TeX into the same dimension as
+`dimen1` if this is at all possible. If `dimen2<1pt` all TeX dimensions
+`dimen1` are attainable. If `dimen2>1pt` not all `dimen1` are
+attainable. If not attainable, the decimal `D` will ensure a closest
+match from below or from above but one does not know if the
+approximation from the other direction is better or worst.
+
+In a sense, this macro divides `<dimen1>` by `<dimen2>` but please continue
+reading this documentation for relevant
+information on how TeX handles dimensions.
+
+## Quick review of basics: TeX points and scaled points
+
+This project requires the e-TeX extensions `\dimexpr` and `\numexpr`.
+The notation `<dim. expr.>` in the macro descriptions refers to a
+*dimensional expression* as accepted by `\dimexpr`. The syntax has some
+peculiarities: among them the fact that `-(...)` (for example `-(3pt)`)
+is illegal, one must use alternatives such as `0pt-(...)` or a
+sub-expression `-\dimexpr...\relax` for example.
+
+TeX dimensions are represented internally by a signed integer which is
+in absolute value at most `0x3FFFFFFF`, i.e. `1073741823`. The
+corresponding unit is called the "scaled point", i.e. `1sp` is `1/65536`
+of one TeX point `1pt`, or rather `1pt` is represented internally as `65536`.
+
+If `\foo` is a dimen register:
+
+- `\number\foo` produces the integer `N` such as `\foo` is the same as `Nsp`,
+
+- inside `\numexpr`, `\foo` is replaced by `N`,
+
+- `\the\foo` produces a decimal `D` (with at most five places) followed
+ with `pt` (catcode 12 tokens) and this output `Dpt` can serve as input
+ in a dimen assignment to produce the same dimension as `\foo`. One can
+ also use the catcode 11 characters `pt` for this. Digits and decimal
+ mark must have their standard catcode 12.
+
+When TeX encounters a dimen denotation of the type `Dpt` it will
+compute `N` in a way equivalent to `N = round(65536 D)` where ties are
+rounded away from zero. Only 17 decimal places of `D` are
+kept as it can be shown that going beyond can not change the result.
+
+When `\foo` has been assigned as `Dpt`, `\the\foo` will produce some
+`Ept` where `E` is not necessarily the same as `D`. But it is guaranteed
+that `Ept` defines the same dimension as `Dpt`.
+
+## Further units known to TeX on input
+
+TeX understands on input further units: `bp`, `cm`, `mm`, `in`, `pc`,
+`cc`, `nc`, `dd` and `nd`. It also understands font-dependent units
+`ex` and `em`, and PDFTeX adds the `px` dimension unit. Japanese
+engines also add specific units.
+
+The `ex`, `em`, and `px` units are handled somewhat differently by
+(pdf)TeX than `bp`, `cm`, `mm`, `in`, `pc`, `cc`, `nc`, `dd` and `nd`
+units. For the former (let's use the generic notation `uu`), the exact
+same dimensions are obtained from an input `D uu` where `D` is some
+decimal or from `D <dimen>` where `<dimen>` stands for some dimension
+register which records `1uu` or `\dimexpr1uu\relax`. In contrast, among
+the latter, i.e. the core TeX units, this is false except for the `pc`
+unit.
+
+TeX associates (explicitly for the core units, implicitly for the units
+corresponding to internal dimensions) to each unit `uu` a fraction `phi`
+which is a conversion factor. For the internal dimensions `ex`, `em`,
+`px` or in the case of multiplying a dimension by a decimal, this `phi`
+is morally `f/65536` where `f` is the integer such that `1 uu=f sp`.
+For core units however, the hard-coded ratio `n/d` never has a
+denominator `d` which is a power of `2`, except for the `pc` whose
+associated ratio factor is `12/1` (and arguably for the `sp` for which
+morally `phi` is `1/65536` but we keep it separate from the general
+discussion).
+
+Here is a table with the hard-coded conversion factors:
+
+ uu phi reduced real approximation 1uu in sp= \the<1uu>
+ (Python output) [65536phi]
+ -- ---------- ------- ------------------ --------- ----------
+ bp 7227/7200 803/800 1.00375 65781 1.00374pt
+ nd 685/642 same 1.0669781931464175 69925 1.06697pt
+ dd 1238/1157 same 1.070008643042351 70124 1.07pt
+ mm 7227/2540 same 2.8452755905511813 186467 2.84526pt
+ pc 12/1 12 12.0 786432 12.0pt
+ nc 1370/107 same 12.80373831775701 839105 12.80373pt
+ cc 14856/1157 same 12.84010371650821 841489 12.8401pt
+ cm 7227/254 same 28.45275590551181 1864679 28.45274pt
+ in 7227/100 same 72.27 4736286 72.26999pt
+
+The values of `1uu` in the `sp` and `pt` units are irrelevant and even
+misleading regarding the TeX parsing of `D uu` input. Notice for
+example that `\the\dimexpr1bp\relax` gives `1.00374pt` but the actual
+conversion factor is `1.00375`.
+
+When TeX parses an assignment `U uu` with a decimal `U` and a unit `uu`,
+be it a core unit, or a unit corresponding to an internal dimension,
+it first handles `U` as with the `pt` unit.
+This means that it computes `N = round(65536*U)`. It then multiplies
+this `N` by the conversion factor `phi` and truncates towards zero the
+mathematically exact result to obtain an integer `T`:
+`T=trunc(N*phi)`. The assignment `Uuu` is concluded by defining the
+value of the dimension to be `Tsp`.
+
+Regarding the core units, we always have `phi>1`.
+The increasing
+sequence `0<=trunc(phi)<=trunc(2phi)<=...` is thus *strictly increasing*
+and, as `phi` is never astronomically close to `1`,
+**it always has jumps**: not all TeX dimensions can be obtained from an
+assignment using a core unit distinct from the `pt` (and `sp` of course,
+but we already said it was kept out of the discussion here).
+
+On the other hand when `phi<1`, then the sequence `trunc(N phi)` is not
+strictly increasing, already because `trunc(phi)=0` and besides here
+`phi=f/65536`, so the `65536` integers `0..65535` are mapped to `f`
+integers `0..(f-1)` inducing non one-to-oneness. But
+all integers in the `0..(2**30-1)` range will be attained for some input,
+so there is surjectivity.
+
+The "worst" unit is the largest i.e. the `in` whose conversion factor is
+`72.27`. The simplest unit to understand is the `pc` as it corresponds
+to an integer ratio `12`: only dimensions which in scaled points are
+multiple of `12` are exactly representable in the `pc` unit.
+
+This also means that some dimensions expressible in one unit may not be
+available with another unit. For example, and perhaps surprisingly,
+there is no decimal `D` which would achieve `1in==Dcm`: the "step"
+between attainable dimensions is `72--73sp` for the `in` and `28--29sp`
+for the `cm`, and as `1in` differs internally from `2.54cm` by only
+`12sp` it is impossible to adjust
+either the `in` side or the `cm` side to obtain equality.
+
+In particular `1in==2.54cm` is **false** in TeX, but it is true that
+`100in==254cm`... (it is already true that `50in==127cm`). It is also
+false that `10in==25.4cm` but it is true that `10in==254mm`... It is
+false though that `1in==25.4mm`!
+
+ >>> (\dimexpr1in, \dimexpr2.54cm);
+ @_1 4736286, 4736274
+ >>> (\dimexpr10in, \dimexpr25.4cm);
+ @_2 47362867, 47362855
+ >>> (\dimexpr100in, \dimexpr254cm);
+ @_3 473628672, 473628672
+
+ >>> (\dimexpr1in, \dimexpr25.4mm);
+ @_4 4736286, 4736285
+ >>> (\dimexpr10in, \dimexpr254mm);
+ @_5 47362867, 47362867
+
+`\maxdimen` can be expressed only with `pt`, `bp`, and `nd`. For the
+other core units the maximal attainable dimensions in `sp` unit are given in
+the middle column of the next table.
+
+ maximal allowed the corresponding minimal TeX dimen denotation
+ (with 5 places) maximal attainable dim. causing "Dimension too large"
+ --------------- ------------------------- --------------------------
+ 16383.99999pt 1073741823sp (=\maxdimen) 16383.99999237060546875pt
+ 16322.78954bp 1073741823sp (=\maxdimen) 16322.78954315185546875bp
+ 15355.51532nd 1073741823sp (=\maxdimen) 15355.51532745361328125nd
+ 15312.02584dd 1073741822sp 15312.02584075927734375dd
+ 5758.31742mm 1073741822sp 5758.31742095947265625mm
+ 1365.33333pc 1073741820sp 1365.33333587646484375pc
+ 1279.62627nc 1073741814sp 1279.62627410888671875nc
+ 1276.00215cc 1073741821sp 1276.00215911865234375cc
+ 575.83174cm 1073741822sp 575.83174896240234375cm
+ 226.70540in 1073741768sp 226.70540618896484375in
+
+Perhaps for these various peculiarities with dimensional units, TeX does
+not provide an output facility for them similar to what `\the` achieves for
+the `pt`.
+
+## Macros of this package (full list)
+
+The macros are all expandable, and most are f-expandable (check the
+source code). They parse their arguments via `\dimexpr` so can be nested
+(with appropriate units added, as the outputs always are bare decimal
+numbers).
+
+Negative dimensions behave as if replaced by their absolute value, then
+at last step the sign (if result is not zero) is applied (so "down" means
+"towards zero", and "up" means "away from zero").
+
+Remarks about "Dimension too large" issues:
+
+1. For input `X` equal to (or sufficiently close to) `\maxdimen` and
+ those units `uu` for which `\maxdimen` is not exactly representable
+ (i.e. all core units except `pt`, `bp` and `nd`), the output `D` of the
+ "up" macros `\texdimen<uu>up{X}`, if used as `Duu` in a dimension
+ assignment or expression, will (naturally) trigger a "Dimension too
+ large" error.
+2. The same potentially happens with `\texdimenwithunit{dimen1}{dimen2}`
+ if `\maxdimen`
+ is not representable exactly by `dimen2` used as a base dimension,
+ (which may happen only if `dimen2>1pt`): it is possible that the
+ output `D`, if consequently used as `D\dimexpr dimen2\relax` will
+ trigger "Dimension too large".
+3. For `dd`, `nc` and `in`, and input `X` equal to (or sufficiently
+ close to) `\maxdimen` it turns out that `\texdimen<uu>{X}` produces
+ an output `D` such that `Duu` is the first "virtually attainable" TeX
+ dimension *beyond* `\maxdimen`. Hence here also `Duu` will trigger on use
+ "Dimension too large error".
+4. Again for the `dd`, `nc` and `in` units, both the "down" and "up" macros
+ will trigger "Dimension too large" *during their execution* if used
+ with an input equal to (or sufficiently close to) `\maxdimen`.
+
+`\texdimenpt{<dim. expr.>}`
+
+> Does `\the\dimexpr <dim. expr.> \relax` then removes the `pt`.
+
+`\texdimenbp{<dim. expr.>}`
+
+> Produces a decimal (with up to five decimal places) `D` such that `Dbp`
+> represents the dimension exactly if possible. If not possible it
+> will differ by `1sp` from the original dimension, but it is not
+> known in advance if it will be above or below.
+
+> `\maxdimen` on input produces `16322.78954` and indeed is realized as
+> `16322.78954bp`.
+
+`\texdimenbpdown{<dim. expr.>}`
+
+> Produces a decimal (with up to five decimal places) `D` such that `Dbp`
+> represents the dimension exactly if possible. If not possible it
+> will be smaller by `1sp` from the original dimension.
+
+`\texdimenbpup{<dim. expr.>}`
+
+> Produces a decimal (with up to five decimal places) `D` such that `Dbp`
+> represents the dimension exactly if possible. If not possible it
+> will be larger by `1sp` from the original dimension.
+
+`\texdimennd{<dim. expr.>}`
+
+> Produces a decimal (with up to five decimal places) `D` such that `Dnd`
+> represents the dimension exactly if possible. If not possible it
+> will differ by `1sp` from the original dimension, but it is not
+> known in advance if it will be above or below.
+
+> `\maxdimen` on input produces `15355.51532` and indeed is realized as
+> `15355.51532nd`.
+
+`\texdimennddown{<dim. expr.>}`
+
+> Produces a decimal (with up to five decimal places) `D` such that `Dnd`
+> represents the dimension exactly if possible. If not possible it
+> will be smaller by `1sp` from the original dimension.
+
+`\texdimenndup{<dim. expr.>}`
+
+> Produces a decimal (with up to five decimal places) `D` such that `Dnd`
+> represents the dimension exactly if possible. If not possible it
+> will be larger by `1sp` from the original dimension.
+
+`\texdimendd{<dim. expr.>}`
+
+> Produces a decimal (with up to five decimal places) `D` such that `Ddd`
+> represents the dimension exactly if possible. If not possible it
+> will differ by `1sp` from the original dimension, but it is not
+> known in advance if it will be above or below.
+
+> Warning: the output for `\maxdimen` is `15312.02585` but `15312.02585dd`
+> will trigger "Dimension too large" error.
+> `\maxdimen-1sp` is attainable via `15312.02584dd`.
+
+`\texdimendddown{<dim. expr.>}`
+
+> Produces a decimal (with up to five decimal places) `D` such that `Ddd`
+> represents the dimension exactly if possible. If not possible it
+> will be smaller by `1sp` from the original dimension.
+
+`\texdimenddup{<dim. expr.>}`
+
+> Produces a decimal (with up to five decimal places) `D` such that `Ddd`
+> represents the dimension exactly if possible. If not possible it
+> will be larger by `1sp` from the original dimension.
+
+`\texdimenmm{<dim. expr.>}`
+
+> Produces a decimal (with up to five decimal places) `D` such that `Dmm`
+> represents the dimension exactly if possible. If not possible it
+> will either be the closest from below or from above, but it is not
+> known in advance which one (and it is not known if the other choice
+> would have been closer).
+
+> `\maxdimen` as input produces on output `5758.31741` and indeed the
+> maximal attainable dimension is `5758.31741mm` (`1073741822sp`).
+
+`\texdimenmmdown{<dim. expr.>}`
+
+> Produces a decimal (with up to five decimal places) `D` such that `Dmm`
+> represents the dimension exactly if possible. If not possible it
+> will be largest representable dimension smaller than the original one.
+
+`\texdimenmmup{<dim. expr.>}`
+
+> Produces a decimal (with up to five decimal places) `D` such that `Dmm`
+> represents the dimension exactly if possible. If not possible it
+> will be smallest representable dimension larger than the original one.
+
+`\texdimenpc{<dim. expr.>}`
+
+> Produces a decimal (with up to five decimal places) `D` such that `Dpc`
+> represents the dimension exactly if possible. If not possible it
+> will be the closest representable one (in case of tie, the approximant
+> from above is chosen).
+
+> `\maxdimen` as input produces on output `1365.33333` and indeed the
+> maximal attainable dimension is `1365.33333pc` (`1073741820sp`).
+
+`\texdimenpcdown{<dim. expr.>}`
+
+> Produces a decimal (with up to five decimal places) `D` such that `Dpc`
+> represents the dimension exactly if possible. If not possible it
+> will be largest representable dimension smaller than the original one.
+
+`\texdimenpcup{<dim. expr.>}`
+
+> Produces a decimal (with up to five decimal places) `D` such that `Dpc`
+> represents the dimension exactly if possible. If not possible it
+> will be smallest representable dimension larger than the original one.
+
+`\texdimennc{<dim. expr.>}`
+
+> Produces a decimal (with up to five decimal places) `D` such that `Dnc`
+> represents the dimension exactly if possible. If not possible it
+> will either be the closest from below or from above, but it is not
+> known in advance which one (and it is not known if the other choice
+> would have been closer).
+
+> Warning: the output for `\maxdimen` is `1279.62628` but `1279.62628nc`
+> will trigger "Dimension too large" error.
+> `\maxdimen-9sp` is attainable via `1279.62627nc`.
+
+`\texdimenncdown{<dim. expr.>}`
+
+> Produces a decimal (with up to five decimal places) `D` such that `Dnc`
+> represents the dimension exactly if possible. If not possible it
+> will be largest representable dimension smaller than the original one.
+
+`\texdimenncup{<dim. expr.>}`
+
+> Produces a decimal (with up to five decimal places) `D` such that `Dnc`
+> represents the dimension exactly if possible. If not possible it
+> will be smallest representable dimension larger than the original one.
+
+`\texdimencc{<dim. expr.>}`
+
+> Produces a decimal (with up to five decimal places) `D` such that `Dcc`
+> represents the dimension exactly if possible. If not possible it
+> will either be the closest from below or from above, but it is not
+> known in advance which one (and it is not known if the other choice
+> would have been closer).
+
+> `\maxdimen` as input produces on output `1276.00215` and indeed the
+> maximal attainable dimension is `1276.00215cc` (`1073741821sp`).
+
+`\texdimenccdown{<dim. expr.>}`
+
+> Produces a decimal (with up to five decimal places) `D` such that `Dcc`
+> represents the dimension exactly if possible. If not possible it
+> will be largest representable dimension smaller than the original one.
+
+`\texdimenccup{<dim. expr.>}`
+
+> Produces a decimal (with up to five decimal places) `D` such that `Dcc`
+> represents the dimension exactly if possible. If not possible it
+> will be smallest representable dimension larger than the original one.
+
+`\texdimencm{<dim. expr.>}`
+
+> Produces a decimal (with up to five decimal places) `D` such that `Dcm`
+> represents the dimension exactly if possible. If not possible it
+> will either be the closest from below or from above, but it is not
+> known in advance which one (and it is not known if the other choice
+> would have been closer).
+
+> `\maxdimen` as input produces on output `575.83174` and indeed the
+> maximal attainable dimension is `575.83174cm` (`1073741822sp`).
+
+`\texdimencmdown{<dim. expr.>}`
+
+> Produces a decimal (with up to five decimal places) `D` such that `Dcm`
+> represents the dimension exactly if possible. If not possible it
+> will be largest representable dimension smaller than the original one.
+
+`\texdimencmup{<dim. expr.>}`
+
+> Produces a decimal (with up to five decimal places) `D` such that `Dcm`
+> represents the dimension exactly if possible. If not possible it
+> will be smallest representable dimension larger than the original one.
+
+`\texdimenin{<dim. expr.>}`
+
+> Produces a decimal (with up to five decimal places) `D` such that `Din`
+> represents the dimension exactly if possible. If not possible it
+> will either be the closest from below or from above, but it is not
+> known in advance which one (and it is not known if the other choice
+> would have been closer).
+
+> Warning: the output for `\maxdimen` is `226.70541` but `226.70541in`
+> will trigger "Dimension too large" error.
+> `\maxdimen-55sp` is maximal attainable dimension (via `226.7054in`).
+
+`\texdimenindown{<dim. expr.>}`
+
+> Produces a decimal (with up to five decimal places) `D` such that `Din`
+> represents the dimension exactly if possible. If not possible it
+> will be largest representable dimension smaller than the original one.
+
+`\texdimeninup{<dim. expr.>}`
+
+> Produces a decimal (with up to five decimal places) `D` such that `Din`
+> represents the dimension exactly if possible. If not possible it
+> will be smallest representable dimension larger than the original one.
+
+`\texdimenbothcmin{<dim. expr.>}`
+
+> Produces a decimal (with up to five decimal places) `D` such that `Din`
+> is the largest dimension smaller than the original one and
+> exactly representable both in the `in` and `cm` units.
+
+`\texdimenbothincm{<dim. expr.>}`
+
+> Produces a decimal (with up to five decimal places) `D` such that `Dcm`
+> is the largest dimension smaller than the original one and
+> exactly representable both in the `in` and `cm` units. It thus represents
+> the same dimension as `\texdimenbothcmin{<dim. expr.>}in`.
+
+`\texdimenbothcminpt{<dim. expr.>}`
+
+> Produces a decimal (with up to five decimal places) `D` such that `Dpt`
+> is the largest dimension smaller than the original one and
+> exactly representable both in the `in` and `cm` units. It thus represents
+> the same dimension as the one provided by `\texdimenbothcmin` and
+> `\texdimenbothincm`.
+
+`\texdimenbothincmpt{<dim. expr.>}`
+
+> Same as `\texdimenbothcminpt`.
+
+`\texdimenbothcminsp{<dim. expr.>}`
+
+> Produces an integer (explicit digit tokens) `N` such that `Nsp`
+> is the largest dimension smaller than the original one and
+> exactly representable both in the `in` and `cm` units.
+
+`\texdimenbothincmsp{<dim. expr.>}`
+
+> Same as `\texdimenbothcminsp`.
+
+`\texdimenwithunit{<dim. expr. 1>}{<dim expr. 2>}`
+
+> Produces a decimal `D` such that `D\dimexpr <dim expr. 2>\relax` is
+> considered by TeX the same as `<dim. expr. 1>` if at all possible. If
+> not possible it will be a closest match either from above or below
+> (but one does not know if the other direction is a better or worst
+> match).
+>
+> `\texdimenwithunit{dim}{1bp}` and `\texdimenbp{dim}` are not
+> the same: The former produces a decimal `D` such that `D\dimexpr
+> 1bp\relax` is represented internally as is `dim` if at all possible,
+> whereas the latter produces a decimal `D` such that `D bp` is the one
+> aiming at being the same as `dim`. Using `D\dimexpr 1bp\relax` implies
+> a conversion factor equal to `65781/65536`, whereas `D bp` involves
+> the `803/800` conversion factor.
+
+
+## Extras?
+
+As already stated the "up" and also the "down" macros for the `dd`, `nc`
+and `in` units will trigger "Dimension too large" if used with inputs
+equal to or very near `\maxdimen`. "Safe" variants which are guaranteed
+never to trigger this error but have some extra overhead to filter out
+inputs very close to `\maxdimen` will *perhaps* be provided if there is
+some demand for it.
+
+But of course anyhow the output from the "up" macros if used
+as input with the corresponding unit will be beyond `\maxdimen` if the
+latter is not attainable, i.e. for all units except `bp`, and `nd`
+(and `pt` but there is no "up" macro for it).
+
+The
+dimensions representable with both `in` and `cm` units have the shape
+`trunc(3613.5*k)sp` for some integer `k`. The largest one smaller
+than a given dimension will thus differ from it by at most about `0.055pt`,
+which is also about `0.02mm`.
+
+For example `\texdimenbothincm{1cm}` expands to `0.99994cm` which maps
+internally to `1864566sp` which differs from TeX's `1cm` by only
+`-113sp`. It can be obtained from `0.39368in` or `28.45102pt`.
+
+And `\texdimenbothcmin{1in}` expands to `0.99945in`, maps internally to
+`4733685sp` which differs from TeX's `1in` by `-2601sp`. It can be obtained
+as `2.5386cm` or `72.2303pt`.
+
+Currently the package does not provide analogous approximations from above.
+For the `1in` for example it would be `4737298sp`, i.e. `1.00021in` which
+differs from TeX's `1in` by `+1012sp` and is obtained also as `2.54054cm`
+and `72.28543pt`.
+
+## Acknowledgements
+
+Thanks to Denis Bitouzé for raising an
+[issue](https://github.com/latex3/latex3/issues/953)
+on the LaTeX3 tracker which became the initial stimulus for this package.
+
+Thanks to Ruixi Zhang for reviving the above linked-to thread
+and opening up here [issue #2](https://github.com/jfbu/texdimens/issues/2)
+asking to add handling of the `ex`,`em`, and `px` cases. This was done
+at release `0.99` via the addition of `\texdimenwithunit`.
+
+<!--
+-->