POSIX specifies the behavior of a shell. This tells Chet how he has to make Bash behave (with some leeway). There are all kinds of silly little details and ambiguities that Chet has to worry about.
However, YOU as a shell script writer do not have to worry about all that crap. All you have to do is put the proper shebang line in your script, and then -- like magic! -- your script will be executed using the interpreter you specified. End of problem.
