Conventionally standard library is part of the language spec. If you look at the C Reference Manual, you'll see that roughly half of the spec is devoted to specifying the stdlib. It would remove a lot of confusion if the set of .magic modules would be named as the standard library and the "standard library" something else.
Also I think that language conformance test suite should not test any modules that are not part of the language spec. Also, Rosetta Code examples should be solved (as much as possible) with the tools provided by language spec, not with help of non-standard modules like strutils or sequtils.
