If you change the value in a base register being used, and want the assembler to compute displacements from this value, you must tell the assembler the new value with another USING statement. In the following sequence, the assembler first assumes that the value of ALPHA is in register 9. The second statement then causes the assembler to assume that ALPHA+1000 is the value in register 9.

         USING           ALPHA,9
         .
         .
         USING           ALPHA+1000,9