To specify a block of text, you press special function keys (or click with a mouse) at the beginning and end of the block. The function keys differ from one word processor to another. Word processors usually display blocks by highlighting them on the screen.

(2) In data management, a block is a group of records on a storage device. Blocks are manipulated as units. For example, disk drives often read and write data in 512-byte blocks.

(3) In network communications, a block is a fixed-size unit of data that is transferred together. For example, the Xmodem protocol transfers blocks of 128 bytes. In general, the larger the block size, the faster the data transfer rate.

(v.) In word processing, to specify a section of text. See definition (1) above. Some applications call this selecting.