LENGTH : Byte Length of a Label:

This directive is not available in MASM. This is used to mention to the length of a data array or a string.

MOV CX. LENGTH ARRAY

This statement is when assembled will substitute the length of the array ARRAY in bytes, in the instruction.

LOCAL the variables, labels, constants or procedures declared LOCAL in a module are to be used only by that module.  At a later time, some other module can be declare specific data type LOCAL, which is previously declared LOCAL by another module or modules.

Thus the similar label may serve different purposes for type different modules of a program. Having a single declaration statement, a number of variables may be declared local, as shown.

LOCAL a, b, DATA, ARRAY, ROUTINE