"The Vesta-2 Software Description Language"
Allan Heydon, Jim Horning, Roy Levin, Timothy Mann, Yuan Yu
Note #1997-005c. June 24, 1997. <a href="http://gatekeeper.dec.com/pub/DEC/SRC/t
echnical-notes/SRC-1997-005c-changes.html">Revised</a> June 2, 1998. 

Vesta-2 is a software configuration management system. Developers use
Vesta-2 to build and manage potentially large scale
software. The instructions for building a software artifact are written
in the Vesta-2 software description language (SDL). Evaluating a
Vesta-2 SDL program causes the artifact to be constructed. 

This note describes the syntax and semantics of the Vesta-2 SDL. It is a
reference manual for use by Vesta-2 users. The language is
functional, uses lexical scoping, and is dynamically typed. It includes
a single primitive function for invoking external tools like
compilers and linkers as function calls.