repeat over referents
     local-declaration*
     action*
  again

A control structure that selects, in turn, each referent defined within the current referents scope. For each iteration, the selected referent is identified as this referent in the body of the repeat over action.

The referents shelf can be combined with programmer-defined shelves in a repeat over action if all the shelves in the repeat over have the same number of items.

This example shows how you can find all of the undefined referents, and list them in the output file. It reports the undefined referent and give it a value that will make it easy to find in the output.

  using output as #error
     repeat over referents
        do when this referent isnt attached
           output key of this referent || "is undefined %n"
           set referent key of this referent to
               "%n%n***" || key of this referent || "***%n%n"
        done
     again