make: how to selectively handle exit status of commands

[Stephan Petersen]

Hi guys,

some external programs I'm calling as commands in rules unfortunately 
return non-zero exit status values even for "warnings", i.e. 
non-critical errors.

What's the best way to deal with such cases, where make should abort for 
*some* exit status values (e.g. > 40), but continue for others (e.g. <= 40).

Thanks in advance for any pointers,

Stephan