[Scheme-reports] Post-plebiscite issue #2: additional character names

[John Cowan <cowan@x>]

(Note that post-plebiscite issue #1 is procedure inequivalence.)

In accordance with Will Clinger's posting, Alexey Radul and I are raising
this issue for the WG1 to resolve after the plebiscite is complete.
I document it now so that WG1 members can discuss it now.

Alexey writes:

> - Additional character names [p.44].  We didn't specify whether 
>   implementations are permitted to define new character names that 
>   begin with "x".  If the remaining characters in the name happened to 
>   be taken from the set [a-f0-9], such a name would give rise to an 
>   ambiguity.  This problem is only mildly fanciful: one could choose 
>   to represent an set of icons as a (non-unicode) character set, and 
>   one could choose to give names to the icons, which one could prefix 
>   with "x" to distinguish them from "normal" characters, leading to a 
>   problem with the name #\xbeef .  It would be advisable not to rule 
>   out all extra names starting with "x", however, because we should 
>   admit #\xi as a name for the greek letter.  Perhaps change 
>   "Implementations are free to add other names." to "Implementations 
>   are free to add other names, so long as those names are not of the 
>   form x[a-fA-F0-9]+ , which would conflict with hex escapes." 

I will add that in addition to xi and Xi, the W3C list of character
entity names for use with XML includes xfr, Xfr, xgr, Xgr, xharr, xhArr,
xlarr, xlArr, xmap, xnis, xodot, xopf, Xopf, xoplus, xotime, xrarr,
xrArr, xscr, Xscr, xsqcup, xuplus, xutri, xvee, xwedge.  Fortunately,
none of these are hex escapes.

I believe Alexey's resolution is correct.  Does any WG1 member disagree?
Does any member of the Scheme community disagree?  Silence gives consent.

-- 
Go, and never darken my towels again!           John Cowan
        --Rufus T. Firefly                      http://ccil.org/~cowan

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