Lambda the Ultimate

Where the word "Call" stands for phone call, not procedure call.

Call Processing Language (CPL): A Language for User Control of Internet Telephony Services

This document defines the Call Processing Language (CPL), a language to describe and control Internet telephony services. It is designed to be implementable on either network servers or user agents. It is meant to be simple, extensible, easily edited by graphical clients, and independent of operating system or signalling protocol. It is suitable for running on a server where users may not be allowed to execute arbitrary programs, as it has no variables, loops, or ability to run external programs.

When I saw the requirement to have no loops I thought about Epigram immediately... If it only was edited easily by graphical clients ;-)

On a serious side - here is a nice example of real life requirement to be NOT Turing complete!