DEC Special Graphics[1] is a 7-bit character set developed by Digital Equipment Corporation.

This was used very often to draw boxes on the VT100 video terminal and the many emulators, and used by bulletin board software.

The designation escape sequence ESC ( 0 (hexadecimal 1B 28 30) switched the codes for lower-case ASCII letters to draw this set, and the sequence ESC ( B (hexadecimal 1B 28 42) switched back.

[2] IBM calls it Code page 1090.

[3]