XSLT 2.0 and XPath 2.0 Programmer's Reference, 4th Edition (771 page)

XTDE0980

The
value
attribute of
xsl:number
must evaluate to a sequence of non-negative integers

A single positive integer is the more usual case.

XTDE1030

The values of sort keys computed for
xsl:sort
must be comparable using
lt

For example, they must not be
xs:duration
or
xs:QName
values, and they must not use a mixture of different types such as strings and integers

XTDE1035

The
collation
attribute of
xsl:sort
must be a collation recognized by the processor

The collation URIs that are recognized will vary from one product to another. If you want your stylesheet to be portable, it's best to pass the collation URIs as the values of stylesheet parameters.

XTDE1110

The
collation
attribute of
xsl:for-each-group
must be a collation recognized by the processor

See XTDE1035.

XTDE1140

The
regex
attribute of
xsl:analyze-string
must evaluate to a valid regular expression

Remember that the
regex
attribute is an attribute value template, so any curly braces need to be doubled.

XTDE1145

The
flags
attribute of
xsl:analyze-string
must evaluate to a valid set of flags

The value must be a string containing one or more of
i
,
m
,
s
, and
x
.

XTDE1150

The
regex
attribute of
xsl:analyze-string
must not evaluate to a regular expression that matches a zero-length string

For example,
regex=“[0-9]*”
matches the string “”, so it is invalid. If “” is a legitimate input value, handle it separately.

XTDE1170

The URI passed to
unparsed-text()
must contain no fragment identifier and must identify a resource containing text

This covers a wide range of things that can go wrong when trying to read an external file.

XTDE1190

The resource retrieved using
unparsed-text()
must be decodable using the specified encoding, and must decode to valid XML characters