summaryrefslogtreecommitdiff
path: root/obsolete/systems/omega/README
diff options
context:
space:
mode:
authorNorbert Preining <norbert@preining.info>2019-09-02 13:46:59 +0900
committerNorbert Preining <norbert@preining.info>2019-09-02 13:46:59 +0900
commite0c6872cf40896c7be36b11dcc744620f10adf1d (patch)
tree60335e10d2f4354b0674ec22d7b53f0f8abee672 /obsolete/systems/omega/README
Initial commit
Diffstat (limited to 'obsolete/systems/omega/README')
-rw-r--r--obsolete/systems/omega/README134
1 files changed, 134 insertions, 0 deletions
diff --git a/obsolete/systems/omega/README b/obsolete/systems/omega/README
new file mode 100644
index 0000000000..4793b07993
--- /dev/null
+++ b/obsolete/systems/omega/README
@@ -0,0 +1,134 @@
+
+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.
+