6 Iteration 6.1 The LOOP Facility 6.1.1 Overview of the Loop Facility 18.104.22.168 Simple vs Extended Loop
22.214.171.124.2 Extended Loop
An extended loop form is one that has a body containing
atomic expressions. When the loop macro processes such a
form, it invokes a facility that is commonly called "the Loop Facility."
The Loop Facility provides standardized access to mechanisms commonly used
in iterations through Loop schemas, which are introduced by loop keywords.
The body of an extended loop form is divided into loop clauses,
each which is in turn made up of loop keywords and forms.