Metrowerks Standard Libraries includes some but not all POSIX functions and types. These extensions are enabled by the macro _POSIX which is defined true by default. This will add both the POSIX function name and the same name with a leading underscore to the namespace.

If _POSIX is turned off by the user then the POSIX names are not defined as part of the MSL headers and only the name preceded by the underscore is available. That is for example in the case of the POSIX function open:

When _POSIX is defined MSL adds both open and _open to the namespace.

When _POSIX is not defined MSL adds only _open to the namespace.

If you wish to disable these function names you will need to merely change the ansi_prefix.xxx.h file, no rebuilding of the library is necessary.