Ex. 1/6: User A requests feature

    +-------------+
    | description |
    | task-tag    | -> public (e.g. mailing list)
    | paym-tag A  |
    | PGP-sig     |
    +-------------+

task-tag: urn:trade:task:userA@a.com:2006-04-10:1
paym-tag: urn:trade:paym:userA@a.com:10$:20$:2006-04-10:2006-04-15:1