APPLMASK is a PORT configuration directive, whose purpose is to
control which applications are connectible at AX25 L2 on the
port.
In this context, "applications" refers to programs which use
XRPi to provide their connectivity with the outside world.
If you want an application to be directly connectible on a
particular port, the application must have an APPLCALL, an
APPLALIAS or both, and the corresponding bit in that port's
APPLMASK must be set.
APPLMASK specifies which applications will be directly
connectible on a given port. The default is 255, which allows
all applications. The value is made up by adding together the
desired selection from the following numbers:
1 - Enable Application 1
2 - Enable Application 2
4 - Enable Application 3
8 - Enable Application 4
16 - Enable Application 5
32 - Enable Application 6
64 - Enable Application 7
128 - Enable Application 8
For example, if a port's definition contains "APPLMASK=9", it
will only allow direct connections to applications 1 and 4 on
that port, providing those applications have either an
APPLCALL or an APPLALIAS.