Allan Shearer wrote:

> I'm struggling with trying to define custom replacements for the 'lt' and 
> 'gt' predefined entities in the ISO_NUM.ent file.

I don't think you can override predefined XML entirties. Here is what 
XML spec says:

"All XML processors MUST recognize these entities whether they are 
declared or not. For interoperability, valid XML documents SHOULD 
declare these entities, like any others, before using them. If the 
entities lt or amp are declared, they MUST be declared as internal 
entities whose replacement text is a character reference to the 
respective character (less-than sign or ampersand) being escaped; the 
double escaping is REQUIRED for these entities so that references to 
them produce a well-formed result. If the entities gt, apos, or quot are 
declared, they MUST be declared as internal entities whose replacement 
text is the single character being escaped (or a character reference to 
that character; the double escaping here is OPTIONAL but harmless). For 
example:

<!ENTITY lt     "&#38;#60;">
<!ENTITY gt     "&#62;">
<!ENTITY amp    "&#38;#38;">
<!ENTITY apos   "&#39;">
<!ENTITY quot   "&#34;">.
"

Instead you can implement general string replace in your XSLT.

-- 
Oleg Tkachenko [XML MVP]
http://blog.tkachenko.com