It is on a set of fields that form a candidate key.

It is on a set of fields that include the primary key.

The data records of the file are organized in the same order as the data entries of the index.

The data records of the file are organized not in the same order as the data entries of the index.

Priority encoder

Decoder

Multiplexer

Demultiplexer

$$-256$$

$$-128$$

$$-127$$

$$0$$

$$xy+x'y'$$

$$x \otimes y'$$

$$x' \otimes y$$

$$x' \otimes y'$$