Explanation of C Compiler for AIX

Hi, I have the following packages installed on my AIX server

xlC.aix50.rte 10.1.0.2 COMMITTED XL C/C++ Runtime for AIX 5.3
xlC.cpp 9.0.0.0 COMMITTED C for AIX Preprocessor
xlC.msg.en_US.cpp 9.0.0.0 COMMITTED C for AIX Preprocessor
xlC.msg.en_US.rte 10.1.0.2 COMMITTED XL C/C++ Runtime
xlC.rte 10.1.0.2 COMMITTED XL C/C++ Runtime


Q1. Are the preprocessors actually a C compiler ?

Q2. Are the above pre-processors some sort of cut down compiler, as I am wondering how this differs from the IBM compiler delivered via vacpp.cmp.tools ?

Q3. What is the Runtime Environment ( RTE ) - how does it differ from the compiler and the linker ( I believe the linker gets installed separately using the xlcpp.util utilities package ? )


any wisdom greatly appreciated,
Jim