Re: Reference to "Alphabetic" in 7.17.2 letter-spacing (XSL 1.1 CR)

The XSL FO SG at its meeting today decided to start the processing of
an erratum to XSL 1.1 as follows:

Change to 7.17.2 letter-spacing:

Replace the paragraph

"For an fo:character that in the Unicode database is classified as
"Alphabetic", unless the treat-as-word-space trait has the value "true",
the space-start and space-end traits are each set to a value as follows:"

with

The set of fo:characters to which the letter-spacing is applied is
implementation defined.

Note: Typically the set is all characters with the following exceptions:
- combining diacritics
- characters where the treat-as-word-space trait has the value "true"
- fixed witdh spaces (U+2000 - U+200B) and dashes (U+2012 - U+2013)
- certain symbols, e.g. box drawing
- characters in scripts where the letters are connected; e.g. Arbaic
- characters in fonts where the letters are connected;
  e.g. a latin "script" font

For the set of fo:characters to which the letter-spacing is applied
the space-start and space-end traits are each set to a value as follows: