> Rule 9: This precludes the use of a construct that is not supported by the C standard. As such it is a pointless rule. I'm not sure that's true. Compilers

> Rule 9: This precludes the use of a construct that is not supported by the C standard. As such it is a pointless rule. I'm not sure that's true. Compilers (let's say, MSVC++) tend to support a mismash of standards and de-facto standards. If you are forbidden from using a construct not supported by the C standard (under which you are building) you are in fact specifying strict compliance with a particular standard, which is meaningful.