regions of physical storage that may be addressed by more than one virtual, or
linear address that are not associated with a memory object, such as VDM UVIRT allocations.
When two memory objects are aliases of each other then they need not have co-incident sizes or origins within the aliased arena record. Aliases are designed to provide alternative attributes for accessing the same piece of data within or across processes. Compare this with shared instance data within the shared arena, where multiple object records share a common arena record. In this case each object is associated with a unique process and is not considered an alias.
Each VMAL is identified by a unique handle referred to as the hal.
Refer to the following for more detailed information