Two hardware flip-flops affect the operation of certain picture symbols: the float flip-flop (FLTF) and the external sign flip-flop (EXTF).

The value of FLTF affects the function performed by the picture symbols D, E, F, J, R, and Z. FLTF is set to 0 (zero) at the beginning of every picture. The picture symbols E, F, and Z can change the value of FLTF to 1, and the picture symbols J, R, and D unconditionally assign the number 0 to FLTF.

The value of EXTF affects the function performed by the picture symbols E, F, J, R, and S. EXTF is not assigned a value by the REPLACE statement that is using the picture; EXTF remains in the state in which it was left after the most recent operation that affected it. For example, a REPLACE statement of the following form sets EXTF to reflect the sign of the first arithmetic expression: the number 0 if the arithmetic expression is positive, and the number 1 if it is negative.

REPLACE <destination> BY <arithmetic expression>
  FOR <arithmetic expression> DIGITS