Programmer Guide/Command Reference/GOTO
GOTO label [fallback_label]
Continue macro execution at the label label. With the argument fallback_label a second label can be specified which is used as the target should the primary target,
label, be undefined. That amazing feature is not available in any other programming language under the sun.
GOTO command is used with a variable label to implement a
switch-like control structure. In this case, fallback_label has the role of the
default switch clause.
If both label, and default_label, are undefined, an error is generated and macro execution terminates.