With one argument, it ROT13's stdin to stdout. With two arguments, it reverses stdin to stdout. With three arguments, it does both. When compiling these versions, one needs to define 'trgpune' in the compile line. It is easy to see that this is unavoidable.
All versions use recursion to work.
I can't use any flow control. This might warrant a warning, since other compilers may do this. I removed such statements to make it more portable. NOON' and 'ABBA' are ROT13 pairs and are palindromes. If your compiler nests comments, it will get this wrong.