VRM
VRM is a model file format supported by 
StudioMDL. It was developed as a successor to SMD, but ultimately was scrapped in favor of sticking with SMD, and later DMX. The main distinction between the formats is that VRM supports multiple LoDs in a single file, using Intel's proprietary Multi-Resolution Mesh (MRM) technology.
Risk of Confusion:The VRM file extension is also used for an unrelated VR model format.