Chico.

A relocatable assembler lets you write modules of code that are independent of each other. Instead of carefully specifying where in memory the "variables" of one module will live, and the variables of another module, and then deciding you really want to move everything about, you use the segment commands to identify the blocks.

Of course, in the assembler, there are ways round it - you can use the ORG command to force the allocation to spaces beginning at (say ORG 1000H.

Variables you want to access from outside the module are handles with the Public and EXTERN commands.

Steve