L2/07-369

Date: Sat, 13 Oct 2007
Source: Martin Duerst
Subject: Changes to UAX#15 re. Stream Safe Text Format

Changes to UAX#15 re. Stream Safe Text Format
=============================================

I'm proposing the following changes to section section 21,
Stream-Safe Text Format, of UAX #15 (currently at
http://www.unicode.org/reports/tr15/tr15-26.html#Stream_Safe_Text_Format).


1. The definitions in section 21 are currently labeled D5 and D6.
   They need to be labeled D7 and D8, because D5 and D6 are already
   used in Section 12.
   (see http://www.unicode.org/reports/tr15/tr15-26.html#D5 and
    http://www.unicode.org/reports/tr15/tr15-26.html#D6)
   [in the following, "D5" and "D6" refer to the current definitions
    in Section 21]

2. Change the following text:
   "Where it modifies an exceptional text, the resulting string would
    no longer canonically equivalent to the original,"
   to:
   "Where it modifies an exceptional text, the resulting string would
    no longer be canonically equivalent to the original,"
   (verb "be" inserted)

3. Change the following text:
   "with the only difference being that reordering is blocked across
    long groups non-starters"
   to:
   "with the only difference being that reordering is blocked across
    long groups of non-starters"
   (preposition "of" inserted)

4. After "D5" or wherever it is thought to be convenient, add a sentence
   along the following lines (details should be verified):
   "NFKD was choosen for the definition of the Stream Safe Text Format/
    Process because it produces the potentially longest sequences of
    non-starters from the same text."

5. At the end of the paragraph after "D6" (starting with
   "The Stream-Safe Text Process ensures not only"), add a sentence
   along the following lines (details should be verified carefully):
   "The Stream-Safe Text Process preserves any of the four normalization
    forms defined in this document (NFC, NFD, NFKC, NFKD). However,
    normalization and the Stream-Safe Text Process do not commute, e.g.
    normalizing an arbitrary text to NFC, followed by the Stream-Safe
    Text Process, is not guaranteed to produce the same result as
    applying the Stream-Safe Text Process to that arbitrary text, followed
    by normalization to NFC."


Please forward this mail as appropriate. I will gladly answer any
email on this subject, but I am not sure I will be able to attend
the UTC. If I'm not able to attend, I'm confident Mark can represent
me on this issue.

Regards,    Martin.


#-#-#  Martin J. Du"rst, Assoc. Professor, Aoyama Gakuin University
#-#-#  http://www.sw.it.aoyama.ac.jp       mailto:duerst@it.aoyama.ac.jp