NEW ISSUE: typo in P0S expires

Title: typo in expires P0S

Description: per the schema spec a zero
second duration needs to have the "T" designator - so it should
be PT0S not P0S.

Justification: align with schema spec
( http://www.w3.org/TR/xmlschema-2/#duration )

Target: core

Proposal: simple search and replace
of P0S with PT0S

easy one  ;-)

-Doug