vt. To exchange two things, each for the
other; to swap places. If you point to two people sitting down and
say "Exch!", you are asking them to trade places. EXCH,
meaning EXCHange, was originally the name of a PDP-10 instruction
that exchanged the contents of a register and a memory location.
Many newer hackers tend to be thinking instead of the PostScript
exchange operator (which is usually written in lowercase).