Originally Timo Noko SDL. Set of telecommunication software programming tools created by Timo Noko in 1978-1990 while mostly employed by Nokia using programming language Nokolisp. Firstly there was the TNGRAPH, a graphical tool to create the SDL-language specification. Then there was the TNANAL to test the overall validity of the specs. And thirdly there was the TNCODE macro processor to produce the actual code to be used in Nokia DX 200 telephone exchange.