Two essential bases are required for the design of reinforcement in reinforced concrete:
The exact geometry of the structure to be executed with recesses and built-in parts (formwork dimensions), and the structural analysis (see Section 4), which, in addition to design information (e.g. maximum bar diameters or minimum spacing), includes the statically required amount of reinforcement for each component and its distribution.
The reinforcement model is modeled as an independent structural design model. 
A structural model is used as the model basis from which the formwork plans can be derived. This formwork model, if you want to call it that, must fulfill both the geometric (LOG) and attributive requirements (LOI) necessary for accurate execution planning.
The reinforcement model created with a BIM authoring tool is then used in the subsequent BIM processes for quality assurance, coordination, quantity takeoff and can also serve as the basis for the automated creation of reinforcement components in prefabrication.