The COMMON attribute specifies that storage for  a  variable  be
  allocated in an overlaid program section called a common block.

  Syntax:

     COMMON [[(identifier)]]

  The 'identifier' indicates the name of the common block.  It  is
  passed  in  uppercase  on  OpenVMS  systems.   If  you  omit the
  identifier, the name of the variable is used as the name of  the
  common block.

  This attribute allows you  to  share  variables  with  other  HP
  languages, such as FORTRAN.

  See the "HP Pascal Language Reference Manual" for  the  complete
  description of using the COMMON attribute.