The mzlib^ signature is defined by:
(define-signature mzlib^ ((open mzlib:core^) (unit compat : mzlib:compat^) (unit print-convert : mzlib:print-convert^) (unit date : mzlib:date^) (unit inflate : mzlib:inflate^) (unit command-line : mzlib:command-line^) (unit restart : mzlib:restart^)))
The mzlib@ unit implements this signature by linking the mzlib:core@ unit together with the non-[CORE] standard library units.