On 05/12/2012 10:40, Taco Hoekwater wrote: >> First, I see that there are five primitives doing the work here: >> \textdir, \mathdir, \pardir, \bodydir and \pagedir. The first two are >> easy enough to understand, and I think I get \pardir (flips where the >> \indent and so forth are). However, I'm not really clear on \bodydir and >> \pagedir: anyone got a good explanation? > > Quoting myself from an older message: > > Taco wrote: >> Roughly put, but I think fairly accurate, is that \bodydir is the >> 'box direction' of \box255, and \pagedir is the initial location of >> the placement origin point on the paper. These have to line up if your >> macro page is not shifting \box255 itself.
Ah right: that explains my experiments (things kept disappearing from the page). I assume these would also make sense at the start of a vbox being used as a 'minipage' (in LaTeX terminology) or similar galley construct. > They are a bit odd in the sense that realistically both of them > are needed once (and exactly once) right at the start of a document, > and that both should have the same value: if they do not agree, text > will normally end up outside of the paper unless the macro package > intervenes explicitly. OK, so at the macro level probably they want to have a single interface. >> Secondly, I'm a bit unsure about the detail on \mathdir when it comes to >> numerals. From what I understand, numbers read in decreasing magnitude >> left-to-right in both LTR and RTL languages, so for example pi is always >> >> 3.1415... >> >> and never >> >> ...5141.3 >> >> even when using (real) Arabic numerals rather than the 'arabic' ones of >> the European tradition. However, \mathdir flips everything: is that >> correct, and if so is the expectation that numerals in math mode are >> handled using a Lua callback? > > A total lack of feedback from an actual knowledgeable person means that > \mathdir does exactly what Aleph did. I *also* suspect it is wrong, but > I am not going to mess with it without a person at hand who can tell me > exactly what *should* happen. Makes sense: perhaps one of the Arabic typesetting experts might step in here and give an opinion :-) -- Joseph Wright
