.pg
.x descriptor
.x descriptor__s
.x descriptor__d
.lt
------------------------------------------------------------------------
DESCRIPTOR	.BLKx  length   pointer  [label]  TYPE=type CLASS=class
DESCRIPTOR_S	.BLKx [length] [pointer] [label] [TYPE=t]  [CLASS=s]
DESCRIPTOR_D	.BLKx [length] [pointer] [label] [TYPE=t]  [CLASS=d]
------------------------------------------------------------------------
.el
.b 3
These macros will allocate the appropriate descriptor structure:
.b
.lt
	DESCRIPTOR	descriptor
	DESCRIPTOR_S	string descriptor
	DESCRIPTOR_D	dynamic string descriptor
.el
.b
If either ^&length\& or ^&pointer\& is not specified, 0 will be used. If
^&pointer\& is specified as the asterisk character (i.e. _*), the appropriate
block storage allocation will be generated.
If ^&label\& is also specified after the asterisk character, then ^&label\&
will refer to the address of the generated block storage allocation.
.b
You must specify the appropriate symbols for ^&type\& and ^&class\&.
.b
BLK^&x\& must be one of the following:
.b
.lt
	.BLKA	reserves storage for addresses (longwords)
	.BLKB	reserves storage for byte data
	.BLKD	reserves storage for double-precision floating-point data
	.BLKF	reserves storage for single-precision floating-point data
	.BLKG	reserves storage for G_floating data
	.BLKH	reserves storage for H_floating data
	.BLKL	reserves storage for longword data
	.BLKO	reserves storage for octaword data
	.BLKQ	reserves storage for quadword data
	.BLKW	reserves storage for word data
.el
.b
For example:
.b
.lt
	var
		string_descr:	descriptor_s	.blkb 512 * string
.el
.b
will generate the following code:
.b
.lt
	string_descr:
		.word	512
		.byte	dsc$k_dtype_t
		.byte	dsc$k_class_s
		.address	3000$
	3000$:
	string:
		.blkb	512
.el