Block data program unit

A block data program unit initializes data values in common blocks. The syntax of a block data program unit is:

BLOCK DATA [block-data-name] [specification-part] END [BLOCK DATA [block-data-name]]

block-data-name

is the name of the block data program unit. Note that the name is optional. If omitted, no more than one unnamed block data program unit may appear in an executable program.

specification-part

is zero or more of the following:

Type declaration statement
USE statement
IMPLICIT statement
COMMON statement
DATA statement
EQUIVALENCE statement
Derived-type definition
The following attribute-specification statements:
- DIMENSION
- INTRINSIC
- PARAMETER
- POINTER
- SAVE
- TARGET

If a USE statement appears in a block data program unit, it makes only the named constants accessible to the program unit.

The block data program unit can initialize more than one common block. However, a common block can be initialized in only one block data program unit. It is not necessary to initialize every object within the common block, but the common block must be completely specified.

As an extension, HP Fortran 90 allows the initialization of objects in blank—or unnamed—common. The following example illustrates this extension:

BLOCK DATA blank
  COMMON//aa(3),ab(5)  ! an unnamed common block
  DATA aa/3*1.0/
  DATA ab/1.0,2.0,3*4.0/
END BLOCK DATA blank

Block data program unit

Technical documentation

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