Error codes in XPath 2.0 specification

Section 2.3.2 of the XPath 2.0 specification [1] defines the format for 
errors as a QName with the format "err:XPYYnnnn". However, throughout 
the rest of the document, and most notably in Appendix F, the error 
category is not included in the QName. For example, syntax errors would 
be err::XPST0003 per Section 2.3.2 but is listed in Appendix F as 
err:XP0003.

Is there a reason for this discrepancy?

Also, is there an explanation for the gaps in the numeric codes?

Thanks in advance for your insight,

     -tree

[1] http://www.w3.org/TR/2005/WD-xpath20-20050211