$DLLRETURN$ and $DLLRETURNSTR$ are assigned values when a .dll is executed using the RUNATSTART, RUNTATMIDDLE, and RUNATEXIT commands and the executed .dll function generates a return value. Many .dlls do not generate return values. If the return value from the .dll is a string instead of a number, the returned string is stored in variable $DLLRETURNSTR$. To specify that the .dll returns a string, check the RunAt Start, RunAtMiddle, RunAtExit commands.