Dear Omegists, Multiple direction support is now included in Omega 1.10. The release can be found at ftp://ftp.cse.unsw.edu.au/pub/users/plaice/Omega/web2c-7.3-omega-1.10.tar.gz Here is the README file. Real documentation will follow. Enjoy! John and Yannis =========================================================================== Release 1.10 includes substantially improved support for multidirectional typesetting. It goes well beyond the support anticipated in the last documentation. Here is some cursory documentation en attendant that the real documentation is prepared with lots of examples. 1. The directions ----------------- It turns out that there are 32 (!) writing directions. They are designated by three-letter codes. The three letters are always T, R, B or L, and they mean, respectively, the Top, Right, Bottom or Left sides of the page. The first letter (the primary direction), corresponds to the side of the page where the first line is to be found. The second letter (the secondary direction), corresponds to the side of the page where the first character of a line is to be found. The third letter (the tertiary direction), corresponds to the orientation of characters within each line. Four directions seem to satisfy the needs of unilingual typesetting for all of the modern scripts. TLT: Left-to-right writing. The most commonly used writing direction. Scripts include LGC scripts, Indic scripts, South-East-Asian scripts, various syllabaries. TRT: Right-to-left writing. Scripts include Hebrew, Arabic and Syriac. RTT: Vertical ideogram writing. Scripts include Chinese, Japanese and Korean. LTL: Vertical cursive writing. Scripts include Mongolian. However, when we start to mix scripts of different directions, a number of interesting combinations appear. The authors have seen the following combinations: RTR: English within a Japanese text. RTL: Arabic within a Japanese text. RBR: Arabic within a Japanese text (starts at bottom of page). LTT: Chinese within a Mongolian text. RTL: Mongolian within a Chinese text. LTR: English or Russian within a Mongolian text. 2. The parameters ----------------- The following parameters are called direction parameters, and they control the behavior of the Omega system. \pagedir The direction for pages (\shipout). \bodydir The direction for vboxes, including the main body of text. \pardir The direction for paragraphs. \textdir The direction for text and hboxes. \mathdir The direction for mathematics. Direction parameters act similarly to other parameters. For example \bodydir RTT changes the direction of the main body of text to RTT. Similarly, \the\mathdir gives the current direction for mathematics. All these parameters respect groups. 3. Additional primitives ------------------------ \pageheight and \pagewidth are new dimensions. The default values for these are for A4 pages. \hbox, \vbox and \vtop can all take a direction parameter. The syntax is \hbox dir TRT ...{...}. The direction must be the first parameter to the box. 4. How it works --------------- Normally, the page and body directions would be set once --- at the beginning --- in the document. Furthermore, in most situations they would be the same. However, for vertical typesetting, it is common for the headers and footers to be horizontal. In that case, the page and body directions would be set to be orthogonal to each other, for Japanese, say, \pagedir TRT\bodydir RTT. The paragraph and text directions would also normally be the same. However, if there are scripts of different directions within the same paragraph, then the text direction would vary. Since the parameter definitions respect the groups, nesting of writing directions is easily done. For example, an English insertion in a Hebrew document would simply be {\textdir TLT\cmr10 An English insertion}. Note that you can get interesting effects, since paragraphs are not group delimiters. The math direction would normally be the same as the text direction. However, real math only works properly for the left-to-right writing directions (TLT, RTR, BRB, LBL). Fake math (used for typesetting tabular in LaTeX) works properly. Note that when a box is begun, then the body, paragraph and text directions all take the same direction as that box. This will be true regardless of whether the direction of the box was given explicitly. 5. Limitations -------------- Not all of the possible interactions will currently give meaningful results. Bidirectional support (TLT and TRT) is complete. Some subtleties in mixed vertical-horizontal writing still need to be worked out.