xml-dev - Comparison of URIs: Character encoding.

[Alan Kennedy <alank@xhaus.com>]

Hello again,

Another question about identifiers, this time URIs.

I need to compare URIs, both as SYSTEM identifiers and Namespace
identifiers. The question I need to answer is this:-

What character encoding should I use for encoding and decoding of
escaped values in URIs?
 
For example: if I see "%7e"("~" in USASCII) in a URI, what character
en(de)coding should I use to map that to a single character for
comparison purposes? What about "%e9" ("e-acute" in "iso-8859-1")?

Another example: If I see a non-USASCII character in an URI,
say "ü" ("u-umlaut"), should I escape that as "%fc", as in 
"iso-8859-1"? Or should I be using UTF-8?

Or is there no such universal mapping?

Again, TIA for any enlightenment.

Alan.