This is a BirthdayBook specification example. {Some remarks about the display: Use IE5 for browsing, it supports XSL; For the display of mathematical symbols, please install Unicode font (, also provided in the Office 2000), after the installation make sure to set the Unicode font as your Web page font; If the page could not be displayed properly (for some IE5, we encountered the same problem before), please update your IE5 to the new version. If you have any problem or suggestion about the demo, please feel free to write to . Thank you.} [DATE,NAME] REPORT == ok &bbar; already_known &bbar; not_known BirthdayBook known &pset; NAME birthday NAME &tfun; DATE known = &dom; birthday InitBirthdayBook BirthdayBook known = ∅ AddBirthday BirthdayBook name? NAME date? DATE name? &nem; known birthday' = birthday &uni; {(name?, date?)} RemoveBirthday BirthdayBook name? NAME name? &mem; known birthday' = {name?} &dsub; birthday ModifyBirthday RemoveBirthday AddBirthday FindBirthday BirthdayBook name? NAME date! DATE name? &mem; known date! = birthday(name?) Remind BirthdayBook today? DATE cards! &pset;NAME cards! = {n : known | birthday(n) = today?} Success result! REPORT result! = 'ok' AlreadyKnown BirthdayBook name? NAME result! REPORT name? &mem; known result! = 'already_known' NotKnown BirthdayBook name? NAME result! REPORT name? &nem; known result! = 'not_known' RAddBirthday AddBirthday Success AlreadyKnown RFindBirthday FindBirthday Success NotKnown RRemind Remind Success RModifyBirthday ModifyBirthday Success