(Or "Scan-In, Scan-Out") A electronic circuit design technique which aims to increase the controllability and observability of a diGItal loGIc circuit by incorporating special "scan reGIsters" into the circuit so that they form a scan path. Some of the more common types of scan design include the multiplexed reGIster designs and {level-sensitive scan design} (LSSD) used extensively by {IBM}. {Boundary scan} can be used alone or in combination with either of the above techniques. ["DiGItal Systems Testing and Testable Design" by Abramovici, Breuer, and Friedman, ISBN 0-7167-8179-4]. ["Design of Testable LoGIc Circuits" by R.G. Bennetts, (Brunel/Southhampton Universities), ISBN 0-201-14403-4]. (1995-02-23)