Unless you have a specific reason otherwise, the following is the One True Spec:
XSPF version 1 (November, 2006)
For historical reasons, you may find the following two versions of the spec useful.
Differences between version 0 and version 1
trackListmay be empty.
datechanged from ISO 8601 to xsd:dateTime.
Because it is easy to make mistakes, those who create XSPF documents should check their output against a validator.