In xsd the whole pattern must match for it to be valid, but with many regex patterns, the pattern only matches part which then returns false.
E.g. With the patern:
<xs:pattern value="[0-9]{1,8}|([0-9]{9,14}|[0-9]{14,14}\.[0-9]+)([+\-][0-9]{1,4})?"/>
When the value is read from the xml document: "20071029130945-0400"
It matches the first part of the regex, i.e. the first 8 chars "20071029" match against [0-9]{1,8}. But in xsd this is invalid as the length of the match is not the same as the length of the whole string.
As a work around, to resolve this you can simply swap the regex around, the the largest match part comes first:
<xs:pattern value="([0-9]{9,14}|[0-9]{14,14}\.[0-9]+)([+\-][0-9]{1,4})|[0-9]{1,8}?"/>
Now the whole string matches.
