Swap/run package functions
 SWPADDENV()                   Increase size of child environment block
 SWPADDSTR() / SWPADDSTRBAS()  Return a string to a previous parent program
 SWPCURDIR()                   Enable or disable saving of the current directory
 SWPDISMSG()                   Enable or disable displaying of message after swap
 SWPEMS320()                   Limit the swapper to using EMS 3.2 calls
 SWPERRLEV()                   Get child process return code
 SWPERRMAJ()                   Get the swap system major error code
 SWPERRMIN()                   Get the swap system minor error code
 SWPFREEMS()                   Limit use of EMS memory for swapping
 SWPFREXMS()                   Limit use of XMS memory for swapping
 SWPGETKEY()                   Enable / disable waiting for a keypress before restoring the parent image
 SWPGETPID() / SWPGETPIDBAS()  Determine if a given program is a parent to the current program
 SWPGETSTR() / SWPGETSTRBAS()  Retrieve string sent from child process via SWPSETSTR()
 SWPKEYBRD() / SWPKEYBRDBAS()  Stuff keystrokes into the child process
 SWPKEYCLR()                   Alter SWPKEYBRD() behaviour
 SWPNOBOOT()                   Prevent the user from rebooting the computer
 SWPRUNCMD() / SWPRUNCMDBAS()  Execute a child process
 SWPSETENV() / SWPSETENVBAS()  Set environment variables for the child process
 SWPSETPID() / SWPSETPIDBAS()  Set a program ID string for the current program
 SWPSETSTR() / SWPSETSTRBAS()  Set a string to return to the parent process
 SWPUSEEMS()                   Enable or disable use of EMS by the swap system
 SWPUSEUMB()                   Enable or disable the use of UMBs by the swap system
 SWPUSEXMS()                   Enable or disable use of XMS memory by the swap system
 SWPVIDMDE()                   Enable or disable restoring of the video page and mode after the swap