There are still other models of interest for linguistics. They are called research models. At input, they take texts in natural language, maybe prepared or formatted in a special manner beforehand. As an output, they produce other texts, usually strictly formatted and representing the contents of dictionaries, grammar tables, rules or anything similar to be used as a part of functional models.
As an example, we can collect all the agreed pairs like “article—noun” or “noun—adjective,” or all the prepositions occurring in an open, i.e., not prepared, text in natural language. As another example, we can extract from the text of a dictionary those items of a given part of speech, which contain a predetermined combination of features.
Thus, research models are tools for constructing functional models. They simulate linguists in their research, whereas the functional models simulate humans in the speech producing and understanding.