Clearing

1. A sequence of events used to disconnect[?] a call and return to the ready state.

2. Removal of data from an AIS, its storage devices, and other peripheral devices with storage capacity, in such a way that the data may not be reconstructed using normal system capabilities (i.e. , through the keyboard).

Note: An AIS need not be disconnected from any external network before clearing takes place. Clearing enables a product to be reused within, but not outside of, a secure facility. It does not produce a declassified product by itself, but may be the first step in the declassification process.

Source: from Federal Standard 1037C and from MIL-STD-188 and from the National Information Systems Security Glossary