Microsoft has many types of licensing modes for its wide range of products, which might look like some kind of military secret codes to those who are not familiar with them.
Below you can find a short brief of each:
CAL - Client Access License
FPP - Full Packaged Product
LVP - License Verification Program
MELP - Microsoft Enterprise License Pack
MLK - Medialess License Kit
MOLP - Microsoft Open License Pack
MVL - Microsoft Variable License
NL - New License
OEM - Original equipment Manufacturer (for new PCs only [up to 3 months])
OLA - Open License Agreement
OPK - OEM Preinstallation Kit
VL - Volume License
For more detailed information on Microsoft Licensing please refer to the following pdf.
More microsoft acronyms refer to the following doc.