I haven't seem much indication from your posts that you can write legible C code at all, never mind "fully portable" code (to the extent that such a thing really exists). Portability is a gradual scale, not an absolute - you can write code that is more or less portable, across a smaller or wider range of targets, compilers and standards. Only a fool considers "portability", in whatever form you mean, to be the main goal for writing C code - it's merely one of the many factors that you can aim for or ignore when writing code. You balance it with things like code legibility and maintainability, code size and speed, programmer productivity, and many other issues that are often far more important in the real world.
Tim is not quite right - I haven't been earning money at embedded programming since before you were born - merely since you were about 5 or 6 years old. There are others in this group who've been at it much longer. You are even trying to argue about C standards with people who not only have been programming C for longer than you've been alive, but who have been heavily involved in defining the standards themselves.
If you want to find some kids to impress with your great knowledge and experience, this is not the place for it. If you want to have a useful discussion, and learn a lot from more experienced developers, and maybe give us a few new ideas too (you don't last in embedded development if you think you know it all), then stick around. Listen to others here, and join in when you're ready to learn.