The jump module is used to pass an acquired identity token for an authenticated user from one system to another for a single sign-on.

It offers a simple API call:
GET /ajax/jump?action=identityToken

Requiring a session identifier and an identifier for the system for which the token is supposed to be generated.

See HTTP-API documentation here:
http://oxpedia.org/wiki/index.php?title=HTTP_API#Module_.22jump.22_.28avai lable_with_v7.6.0.29