According to XML specifications, character range #xF900 to #xFFFE is not
valid. But I tried to use some characters in this range and my SAXParser did
not throw any error (I'm using SAX 2.0 - Xerces 3.2.1- XML4J). Does the SAX Parser not follow all the specifications or is it a bug in the parser?
Implementing restrictions on Unicode character ranges is one area where parsers differ a lot - especially in the area of characters that are permitted within tag and attribute names.
Best to check the documentation for your parser.
Note also that it depends how you encoded the characters in your XML. If you use character entity references for example (豈) these are fine in PCDATA. Other characters can be valid in one encoding (such as ISO-8859-1) supported by many parsers, but illegal in other encodings i.e. US-ASCII.
This was first published in July 2002