Two runtime elements in a run unit can reference common data in the following circumstances:
- The data content of an external data record can be referenced from any runtime element provided that element has described
that data record.
- If a program is contained in another program, both programs can refer to data possessing the global attribute either in the
containing program or in any program which directly or indirectly contains the containing program.
- The mechanism whereby a parameter value is passed by reference from an activating runtime element to an activated runtime
element establishes a common data item; the activated runtime element, which can use a different identifier, can refer to
a data item in the activating runtime element.