Differences between OCaml compiler and manual

So I was reading http://www.podval.org/~sds/ocaml-sucks.html, which includes this quote (in the context of problems with ocaml):

there are actually three mildly different syntaxes:

• the official one is described in the manual
• a superset thereof is accepted by the compiler ocamlc
• something similar (but ever so slightly different) is accepted by the preprocessor Camlp4 (e.g., it accepts List.map [1;2;3] ~f:fun x -> x, which is also accepted by the top-level, but not the compiler)

What are examples of ocaml code fragments that are accepted by the ocamlc but do not match the manual?

PS - I'm mainly interested in OCaml 4.00.1, but previous versions are also interesting...