RE: xsl:sort with msxml english language, danish char

It's up to the implementor whether they support lang="da" or not.

For lang="en", it's up to the implementor how special characters are
collated. This processor appears to be using a fairly commonly used
algorithm in which characters are given a primary weight (a, b, c), and a
secondary weight based on variations of the primary character (accents); the
secondary weight of a character is taken into account only if the primary
weights of all characters are equal.

This algorithm is similar to those used by publishers when foreign-language
names are used in an English publication such as a gazetteer, though I've
seen many variations in the actual practice of different publishers.