> It seems that String is the name of the module structure itself rather
> than its signature. But what is the name of the signature ?
        
Module String is not constrained by a named signature - you either need to
copy the interface from string.mli (it'll be in your ocaml lib directory) or
use ocamlc -i to generate an inferred interface and copy it in (cf. the
Extlib module ExtList.List). If there is another way, then I'd be fascinated
to hear it too!


David