The term "Wide Spectrum Language" (WSL in short) is defined and the introduction of WSL's is motivated. A WSL consists of n layers being programming languages themselves. The basic layer L_o of L, a special WSL, is presented. A survey of the language L_o is given mentioning the main aspects that influenced its development. Comparing L_o with assembly language and ALGOL 68, L_o is located in the hierarchy of known programming languages. The mode-model, a central feature of the language, is treated in more detail.