Special character constants

[Adrian McCarthy]

I only have K&R2, not the Standard.  On a machine whose character set does
not support special characters like tab and backspace, what happens to
character constants like '\t' and '\b'?  Is there some special value they
get set to (e.g., ' ' or '\0') instead?  Or is this issue left undefined?

I'd like to keep some code I'm writing portable to many machines by using
tabs if they are available and emulating them with spaces if they are not.

Aid.  (adrian at gonzo.mti.com)