4 Jan 1999: 'substitution' command is not Unicode-aware;
	substitution rmnbsp [list \xA0 " "]
	rmnbsp "\xA0."
    does not work: the arguments to the definition command end up
    UTF-encoded, while the arguments to the instance command are not.
	
24 Aug 1999: Cost: Multiple versions of Cost (2.1, 2.2) don't like to
	live together on the same system (pkgIndex.tcl, 'set COSTLIB ...')
	(8 Feb 2000: Should be sort-of-fixed now)

KNOWN BUGS IN XML SUPPORT: [26 Jun 1999]

    I've only gotten as far as integrating EXPAT and
    adding the [loadxml] command; it's largely untested so far.
    Problems that I know about:
	+ Does not handle external entities at all;
	+ Does not handle Unicode at all (this should be easy to
	  do under Tcl 8.1, I just haven't learned enough about I18N yet)
	+ XML is case-sensitive, whereas the Cost query language
	  is case-insensitive in several places; need to make sure it's
	  doing the right thing.


Under Windows: $COSTPATH should be ';'-separated, not ':'-separated.
Ought (?) to check registry instead of relying on envars.

Biggest problem:
Cost is way too damn hard to compile and install.
[24 Jun 1999] Should be a bit better now.

[4 Feb 1999]
Errors in parse_query() should go to Tcl_Interp result, not stderr.

[9 Nov 1998] If sgmls encounters too many errors (esp.
if it can't find the DTD), it seems to produce bad ESIS
on stdout.  This hopelessly confuses rdsgmls.c, and can
cause a crash.  Need to robustify rdsgmls.

[30 May 1996] Reentrancy problem with 'loadsgmls' --
loading a new document while in the middle of a query,
event handler, or other Cost primitive can crash the
program. [24 Jun 1999] Fixed, sort of.  Cost now never
frees the old document.

There are a few (rather large) memory leaks, but none are
disastrous for most applications.  In particular, loading a
second or subsequent SGML document does not completely free
earlier ones.  [24 Jun 1999: This is now a feature :-(]

Assumes NAMECASE GENERAL YES ENTITY NO
and an 8-bit document character set.

Treats "record-end" characters as "newline" characters.
[26 Sep 1998] This is probably not a bug in Cost.

Does not distinguish SDATA entity references in
attribute values.

SUBDOC support is a little shaky.  Does not correctly keep track
of entities in subdocuments.

Only supports
    QUANTITY
	NAMELEN 8000	-- default: 8 --
	LITLEN	8000	-- default: 240 --
	PILEN	8000	-- default: 240 --
(8000 is an approximate value.)

Also, more than ~8Kbytes of contiguous character data with no intervening
record-ends or subelements will crash Cost (there is no QUANTITY setting
for this).  Other quantities and all CAPACITYs are limited by available
memory.