test.f90

module commondat
        implicit none
        real, public :: a,b,c
        data a,b,c / -1.0, -1.0, -1.0/
contains
        subroutine outdat()
        write(6,'(1x,"a,b,c=",3f7.2)') a,b,c
        end subroutine outdat
end module commondat

program tcommon
        use commondat
        implicit none
        call suba()
        call subb()
        call subc()
        call outdat()
end program tcommon

subroutine suba()
! USE the module ... it handles all
! the necessary declarations
        use commondat, only : x=>a
        implicit none
        real :: a = 1.0
        x = a
        return
end subroutine suba

subroutine subb()
! ONLY use the variable we need ...
! even rename it,all other are 'invisible'
        use commondat, only : x=>b
        implicit none
        real :: a = 2.0
        x = a
        return
end subroutine subb

subroutine subc()
        use commondat, only : x=>c
! note the rename syntax is same as
! pointer assignment
        implicit none
        real :: a = 3.0
        x = a
        return
end subroutine subc