The AppPath variable is used by Active Call Center to provide the macro with the location of the Active Call Center program folder. AppPath is a read-only variable, and it's value under a default installation is usually "C:\Program Files\Active Call Center" (notice there is no trailing backslash).
AppPath is extremely useful for simplifying filenames, for example:
SpeakWave1 = AppPath & "\Prompt.wav"
Another application:
Record = "Record a message at the beep."
SaveFileAfterRecord = AppPath & "\Message" & CallID & ".wav"