Programmer's Notes for filename: http://www.scribeserver.com/NEUMES/xml/NEUMES_characters.pen
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<!-- Programmer's Notes:
* DO NOT modify comments containing the words "START," or "END,".
* DO NOT modify the literals "index" or "end, index". Maintain consistency of
  the major section titles and the index for automated TOC. [Don't use braces
  here.]
* Q: Why is pes_stratus not pes with stratus qualifier?
* Q: Add vertical episema (above or below, indicating different amounts of
  stress) and following-dot qualifiers? Along with the horizontal episema,
  these are considered as 'rhythmic signs' per the _Liber Usualis_.
* Synonym mnemonics do not need to be added to Long Strings (they are the same
  codepoint).
* Use single-quotes (not double) for quoted strings within code-point
  description Comments.
* non-ASCII characters not allowed in XML comments.
* line_break (end of line) in source MS, use Element:
     
  page_break (end of page) in source MS, use Element:

     
  column_break (end of column) in source MS, use Element:
     
* Some composed neumatic symbols are temporarily encoded as single Entities.
* Long strings of symbol codepoints for XSLT 1.0 char-range checking do not
  include Compatibility Characters, because such characters are expanded by
  the XML preprocessor.
* To-do:
* LB 29/06/06: add chromatic pitches (nono-diatonic) for Eastern
  transcriptions.
* Enter position numbers in normal reading order, regardless of position
  numbers.
* LB 23/08/05: add staff colors; update Schema global_layout_Type.
* [LB 18/1/05: increase staff lines to 8? :: this is 2-staff polyphony]
* To-do: omit 'p' from positive CFs?
* To do: discuss pros/cons of adopting Unicode Standard 4.1 codes for some
  neumatic symbols (viz, doing so would make handling of ranges troublesome).
* To do: compose a rule about capitalization of Entity names.
* To do: Add absolute position numbers: photographic X-Y, or GUI editor X-Y.
* To do: Add quarter-tone Pitches and Tonal Movements.
* Q: add low B-flat to Pitches?
* Q: can pes_subpunctis and torculus_resupinus_subpunctis ever *not* be
  composed?
* For interoperability, valid documents should declare the entities
  'amp', 'lt', 'gt', 'apos', 'quot'.
* 'amp', 'lt', 'gt', 'apos', and 'quot' declarations recommended "for
  compatibility"[?].
* UTF-8 encodes ASCII characters in one byte; up to U+07FF (scalar value
  2^11 - 1) in two bytes (including Latin, standard Greek, Cyrillic, Armenian,
  Hebrew, and Syriac alphabets); and, up to U+FFFF (scalar value 2^16 -1) in
  three bytes (including PUA, Variation Selector-1, and &objReplace;).
* Q: Is performance letter 'perf_s' for sursum (indicating that the next pitch
  is higher than you might expect)?
[End, Programmer's Notes] -->