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diff --git a/Master/texmf-dist/doc/context/sources/general/manuals/bidi/bidi-lua.tex b/Master/texmf-dist/doc/context/sources/general/manuals/bidi/bidi-lua.tex new file mode 100644 index 00000000000..beb93b6049a --- /dev/null +++ b/Master/texmf-dist/doc/context/sources/general/manuals/bidi/bidi-lua.tex @@ -0,0 +1,38 @@ +% language=us + +\startcomponent bidi-lua + +\environment bidi-style + +\startchapter[title={The \LUA\ interface}] + +We assume that you run \CONTEXT\ \MKIV\ in combination with \LUATEX. Direction +support in this engine has been improved over time. Originally the \OMEGA\ +(\ALEPH) direction model was used but in the meantime it has been stripped to the +basics, and what used to be so called whatsits (extension nodes) are now first +class nodes. Of the many directions only four are kept in \LUATEX\ and they are +indicated by three letters: + +\starttabulate[|l|l|l|] +\NC 0 \NC \type {TLT} \NC left to right \NC \NR +\NC 1 \NC \type {TRT} \NC right to left \NC \NR +\NC 2 \NC \type {LTL} \NC not used in context (obsolete) \NC \NR +\NC 3 \NC \type {RTT} \NC not used in context (obsolete) \NC \NR +\stoptabulate + +In \LUAMETATEX, and therefore \CONTEXT\ \LMTX\ we only have the first two. +Therefore in \LMTX\ you normally don't have to worry about checking for them at +the \LUA\ end because they are irrelevant for calculations (the vertical ones +swapped the horizontal and vertical progression). Also, when really needed, we +use the \type {direction} keys with numerical indicators, so zero for \type {l2r} +and one for \type {r2l}. These values are used for local par nodes as well as +direction nodes. In addition a direction node has a subtype: + +\starttabulate[|l|l|l|] +\NC 0 \NC \type {normal} \NC comparable to \type {+} \NC \NR +\NC 1 \NC \type {cancel} \NC comparable to \type {-} \NC \NR +\stoptabulate + +\stopchapter + +\stopcomponent |