Each running Server 2012 OS instance is classified as one of these.
The license limitations of Server 2012 virtual machines are those of the license, not the software. You can, for example, create more than two VMs on a copy of Windows Server 2012 Standard, but you must purchase additional licenses to do so.
Server edition license restriction: POSE - 1, VOSE - 2.
Server edition license restriction: POSE - 1, or VOSE - 1 but not both.
Server edition license restriction: POSE - 1, VOSE - 0.
Hyper-V