A Jump command is the moan equivalent of the TNT Basic Goto command.
Any upper case letter followed by a : declares a label that can be jumped to with a Jump
command. When using the Jump command, the label is not followed by a :
Example:
"A: J A" ' This is an infinite loop
"Arm: J Arm" ' Lower case letters are ignored in labels also
See also TNT Basic's Goto statement.