L2/08-094

Date/Time:    Fri Feb  1 11:30:59 CST 2008
Name:         John Cowan
Report Type:  Feedback on UAX #42

I suggest the following improvements to the RELAX NG in UAX #42 (draft 2):

1) In 4.4.5, it is possible to specify that the mirrored property is
false and that the bmg property has a non-null value.  The following
schema fragment exploits the inter-attribute dependency capabilities
of RNG to make that impossible:

mirrored-yes = attribute Bidi_M { "yes" }
mirrored-no = attribute Bidi_M { "no" }
bmg-maybe = attribute bmg {"" | single-code-point }
bmg-no = attribute bmg {""}

code-point-properties &=
   (mirrored-yes |
   bmg-maybe |
   (mirrored-yes & bmg-maybe) |
   mirrored-no |
   (mirrored-no & bmg-no))?

2) In 4.4.7, a similar treatment expresses the interdependency of
the nt and nv properties:

nt-yes = attribute nt { "De" | "Di" | "Nu" }
nt-no = attribute nt { "None" }
nv-maybe = attribute nv ("" | xsd:string { pattern = "-?[0-9]+(/[0-9]+)?" }}
nv-no = attribute nv { "" }

code-point-properties &=
   (nt-yes |
   nv-maybe |
   (nt-yes & nv-maybe) |
   nt-no |
   (nt-no & nv-no))?


3) In 4.4.8, same story for jt and jg:

jt-yes = attribute jt { "D" | "L" | "R" }
jt-no = attribute jt { "U" | "C" | "T" }
jg-maybe = attribute jg { # fill this in
           }
jg-no = attribute jg { "No_Joining_Group" }

code-point-properties &=
  (jt-yes |
   jg-maybe |
   (jt-yes & jg-maybe) |
   jt-no |
   (jt-no & jg-no))?

4) In 4.4.12, the possible scripts are enumerated. I believe this to
be a mistake, as new scripts are constantly being added. Instead, the
definition should simply require ISO 19542 conformance:

code-point-properties &=
   attribute sc { xs:string { pattern = "[A-Z][a-z]{3}"}}

5) In 4.4.13, both iso and isc are used as attribute names.  Pick one.