A container which defines a physical side of a page of output.
A PAGE element cannot be nested within another PAGE element.
An IDF element cannot be placed in a PAGE element, but an IDF file may be INCLUDEd.
All of the remaining elements - B, DDF, EXECUTE, FIELD, FILE, GROUP, INCLUDE, INFO, M, P, RS2, RTF, SIGNATURE, TEXT - are allowed in the PAGE container. Any attributes of the PAGE become the defaults for items defined within it.

IDF element example
GROUP element example