a storage area that two or more scoping units can share, allowing them to define and reference the same data and to share storage units
(n.) a block of physical storage that may be accessed by any of the scoping units in an executable program
A physical storage area shared by one or more program units. This storage area is defined by a COMMON statement. If the common block is given a name, it is a named common block; if it is not given a name, it is a blank common.