Data Segment : A program's data segment contains all the variable definitions. Constant definitions are often made here as well, but they may be placed elsewhere in the program since no memory allocation is involved. To declare a data segment, we use the directive. DATA, followed by variable and constant declarations.
.DATA DW 2
WORD1 DW 5
WORD2 DB 'THIS IS A MESSAGE'MASK EQU 10010010B