Abstract: Function model is the kernel processing object of the conceptual design. First, a
function-model format language (FFL) is proposed based on the analysis of function tree and
extenics function model. The reatures of FFL are summarized and the definition and grammar are
given. Second, an algorithm of conversion from extenics function model to function tree is put
forward. Lastly, an example testifies the important role of FFL in promoting the connections
among function models.

Key words: conceptual design, function model, function-model format language, extenics;