First (in fact one and only) interpreter of Blank language was written during two-day (night?) marathon by Andy Turley. His inspiration was brilliant Befunge interpreter, created by Chris Pressey.

Blank has rather limited instruction set (one character per instruction). All Blank's instructions are enclosed in curly brackets. All numbers are delimited by square brackets (it simplifies significantly entering of number values).
There are instructions for doing jumps, decision making and code self-modification, too.

At the moment I'm the maintainer of both Blank sources and this page. There are some fix-ups (screw-ups ;) of original code, HTMLized user guide, highlight file for Vim editor and man page for Lunix users.