The ETAC programming language is, arguably, the first of an evolutionary step of dictionary and stack based token activated programming languages, capable of full traditional high-level block structured syntax with the versatility and efficiency of a token activated stack-based language. A token activated programming language operates by sequentially activating text tokens, but not necessarily in one direction only. ETAC is a token activated language that uses 'sequential reverse-flow activation' which activates programmer-determined groups of tokens sequentially from left to right, but the tokens in each group are activated from right to left ('reverse-flow'). This allows the programming language to be written in groups using prefix notation as the programmer desires. It also allows the designer of the programming language to implement high-level block structured syntax, as is usual for traditional programming languages.
