— procedure: user-id? object –> boolean
— procedure: user-id=? uid_a uid_b –> boolean
— procedure: user-id->integer uid –> integer
— procedure: integer->user-id integer –> uid
— procedure: group-id? object –> boolean
— procedure: group-id=? gid_a gid_b –> boolean
— procedure: group-id->integer gid –> integer
— procedure: integer->group-id integer –> gid

User-id? & group-id? are the disjoint type predicates for user & group ids. User-id=? & group-id=? test whether two user or group ids, respectively, are the same, i.e. whether their numbers are equal. User-id->integer, group-id->integer, integer->user-id, & integer->group-id convert between user or group ids and integers.

— procedure: user-id->user-info uid –> user-info
— procedure: name->user-info string –> user-info
— procedure: group-id->group-info gid –> group-info
— procedure: name->group-info string –> group-info

These provide access for the user or group info records that correspond with the given user or group ids or names.

— procedure: user-info? object –> boolean
— procedure: user-info-name user-info –> string
— procedure: user-info-id user-info –> user-id
— procedure: user-info-group user-info –> group-id
— procedure: user-info-home-directory user-info –> string
— procedure: user-info-shell user-info –> string
— procedure: group-info? object –> boolean
— procedure: group-info-name group-info –> string
— procedure: group-info-id group-info –> group-id
— procedure: group-info-members group-info –> user-id-list

User-info? & group-info? are the disjoint type predicates for user info & group info records. The others are accessors for the various data available in those records.