Hi Esther,

I'm guessing that you are referring to the verb s'asseoir - to sit.

The only three impératif mood forms  are    assois-toi       (assieds)

                                                                        assoyons-nous (asseyons)

                                                                         assoyez-vous (asseyez)

Hope this helps

Jim

Jim is correct - there are only 3 forms for the imperative. There are 2 accepted forms of the imperative verb commands for s'ass(e)oir - covered in the attached.

Conjugate reflexive verbs in the imperative mood in French (L'Impératif) - affirmative commands

I can't provide data, or absolutely swear to it, but my experience (which is limited and could be influenced strongly by regional exposure) is that the first listed set of imperatives in the lesson are the more often used group, although both are definitely acceptable.