Sign - Picture clause:
The numeric data item can be signed or unsigned. If a numeric data is regarded as unsigned then during the execution these unsigned data items are treated as positive quantities.
To explain a signed data item one must use the code character S at the leftmost end of the picture clause of the corresponding variable.
It is very important to note that internally, the operational sign (S) is not stored as a separate character. The operational sign is stored at zone bits of the rightmost digit place of the data item. While preparing a data for such an input-signed item, care must be taken to ensure that the data appears on the input medium in similar form.