> Does anyone know why the code generated by camlidl does not use the
> CAMLxxx macros that are specified by the OCaml manual?

The API for GC root registration went through several design cycles,
and CamlIDL was mostly written before the latest API (the CAMLxxx
macros) was implemented.  Besides, the Begin_roots* macros used in
CamlIDL-generated code, while lower-lever than the CAMLxxx macros,
are no harder, and maybe slightly simpler, to generate automatically
by a program such as CamlIDL.

- Xavier Leroy