XSLT 2.0 and XPath 2.0 Programmer's Reference, 4th Edition (98 page)

XPath provides a number of operators and functions that act on or return numeric values:

• The numerical comparison operators
  <
  ,
  <=
  ,
  >
  , and
  >=
  . Within a stylesheet, you may need to use XML escape conventions to write these, for example,
  <
  in place of
  <
  .
  
• The numerical equality operators
  =
  and
  !=
  .