Under OS/2 one LDT is allocated per process except for VDMs in which multiple LDTs are possible. A VDM will allocate one LDT per DPMI client, but if it does not use DPMI then the LDT is not initialised. When multiple LDTs are used in a VDM then the LDTR descriptor contents are updated to make an LDT current. This allows the same LDTR selector may be use regardless of current client.
Refer to the following for more detailed information: