# Defining Accelerator Capabilities

An accelerator can be used in restricted operation, in which case it conforms to a restricted profile, or it can be used in nonrestricted operation, in which case it does not conform to a restricted profile.

### Restricted Operation

The capabilities of an accelerator are defined according to which restricted profile it supports. An accelerator may support one or more restricted profiles.

Some restricted profiles are defined as subsets of the capabilities of other restricted profiles (for example, the MPEG2_A profile is a subset of the capabilities of the MPEG2_B profile). Accelerators that support a particular restricted profile must also support any restricted profile that is a subset of the profile being supported. For example, accelerators that support the MPEG2_B profile must also support the MPEG2_A profile.

### Nonrestricted Operation

If in DirectX VA an accelerator is used without strict conformance to a restricted profile, the wRestrictedMode member of the DXVA_ConnectMode structure must be set to 0xFFFF to indicate this lack of restriction.

All defined values of the bDXVA_Func variable are allowed.