I have found in http://en.wikipedia.org/wiki/C99 that Pelles C has full support for C99.
However I have doubts.
As probably you know, the GCC project has not yet reached full support for C99. The details in which GCC is conforming or not are very well documented. However, I cannot understand what exactly means that Pelles C is fully conforming.
Is it conforming for every computer and operating system?
For example, GCC (under command line option -std=c99) is compliant with ISO/IEC IEEE 60559 (floating point standard) if the hardware is perfectly compliant.
http://gcc.gnu.org/c99status.html
Is Pelles C concerned with this level of detail? I don't feel sure about the claims that Pelles C is C99 conforming.