In France, the lively question of training content has been brought back to the forefront by the arrival of a new recruitment examination and a new reform of pre-and in-service schoolteacher training. Since 2013, the institution has listed general skills that teachers should master to practice their profession, but it does not mention specific knowledge required to teach mathematics. In the absence of a sufficiently precise framework, the tricky issue of required knowledge is left to teacher trainers. Faced with this lack, a collective of trainers and researchers to which we belong, the COPIRELEM group, has developed a framework document for schoolteacher trainers in mathematics education. In this paper, we study the design process of this resource.