The BIM Forum of the Associated General Contractors has released for public comment a draft specification for levels of development of building information models. Interested parties have until June 7 to comment on the draft, which has been under development for two years by a committee of about 20 people.

The 132-page document defines and illustrates characteristics of model elements of different building systems at different levels of development. It is intended as a reference to enable practitioners to specify “with a high level of clarity” the content and reliability of BIMs at various stages in the design and construction process. The goal is for model authors to be able to define for downstream users the specific uses and limitations of their models, says the BIM Forum.

The document's release is scheduled for August, depending on the commentary received. Interested parties can get an electronic copy of the draft by registering at The final specification will be made available at no charge.