The Event Manager Framework uses a Sockets "select" call to wait on multiple sockets. At the time of EMan creation, the SOMEEMan class object loads one of the Sockets subclass DLLs, based on the value of the environment variable SOMSOCKETS. This environment variable should name the implementation class of sockets (see Appendix E describing the Sockets abstract class and the specific implementation DLLs available with the SOMobjects Toolkit.) The current choices for this environment variable are TCPIPSockets, (and TCPIPSockets32 for OS/2), NBSockets, and IPXSockets .