Processing Unicode complex text

ACIF supports input data sets that contain complex text, which is Unicode-encoded text that cannot be translated with the traditional one-code-point to one-glyph method; for example, bidirectional Arabic text or combined Hindi characters. Complex text requires:

  • Extra processing.
  • Identification with a PTOCA Unicode Complex Text or Glyph Layout Control (GLC) control sequence.
  • A layout engine that examines runs of code points and maps the code points to runs of glyph indexes and their positions.
  • TrueType and OpenType fonts.

Font layout tables contain script-specific information about glyph substitution, glyph positioning, justification, and baseline positioning, all of which are used by the layout engine to translate complex text.

For ACIF to correctly process GLC control sequences, the TrueType and OpenType fonts that are used must be placed inline in the print data set. ACIF looks in the inline resource group for the font that is referenced in the Map Data Resources (MDR) structured field. If ACIF cannot find the font inline, the complex text is not processed.