WSDL: Web Services Description Language

It is an XML vocabulary for describing web services.

1.0 was published independently in late 2000.

1.1 was published as a W3C note in 2001 (no working group).

There is now a working group at the W3C that works on WSDL.

1.2 became 2.0 due to many changes in the structure/syntax.

The 2.0 specification is still a working draft.