MACRO-64 has the following 11 block storage directives: DirectivReserves Storage for: Bytes Allocated .BLKA Addresses (quadwords) 8 * value of expression .BLKB Byte data Value of expression .BLKD Double-precision 8 * value of expression floating-point data (quadwords) .BLKF Single-precision 4 * value of expression floating-point data (longwords) .BLKG G_floating data 8 * value of expression (quadwords) .BLKL Longword data 4 * value of expression .BLKO Octaword data 16 * value of expression .BLKQ Quadword data 8 * value of expression .BLKS S_floating data 4 * value of expression (longwords) .BLKT T_floating data 8 * value of expression (quadwords) .BLKW Word data 2 * value of expression Each directive reserves storage for a different data type. The value of the expression determines the number of data items for which MACRO-64 reserves storage. For example, .BLKL 4 reserves storage for 4 longwords of data and .BLKB 2 reserves storage for 2 bytes of data. The total number of bytes reserved is equal to the length of the data type times the value of the expression.