Standard: F77 F90 F95 F2003
EQUIVALENCE eqv-set [ , eqv-set ]...

eqv-set ::= ( obj, obj [ , obj ]... )

obj ::= name  |  array-element  |  substring
The EQUIVALENCE statement causes variables to share the same memory locations. The variables must have the same type and kind, except that default real, double precision real, default complex, default integer and default logical may be equivalenced together.

This feature is very error-prone and its use is strongly discouraged.
COMMON statement, ENTRY statement