OS/2 2.0 provides portability for the current set of DOS applications by adhering to current industry standards for personal computing. The ability of OS/2 2.0 to execute DOS applications that use eXtended Memory Specification (XMS) Version 2.0, Expanded Memory Specification (EMS) Version 4.0, and DOS Protected Mode Interface (DPMI Level .9) prevents existing DOS applications from becoming obsolete due to migration to OS/2 2.0. Many DOS applications use these memory extenders to gain access to memory above the 1MB real-mode addressing limit. Such extenders allow DOS applications to have total code and data spaces larger than the available base conventional memory, and to have very large code or data objects loaded into memory for improved speed.