This function allows the introduction of new severity classes
which can be addressed by the
argument of the
By default that latter function only knows how to
print messages for severity 0-4 (with strings (none), HALT,
ERROR, WARNING, INFO).
This call attaches the given string
to the given value
is NULL, the severity class with the numeric value
It is not possible to overwrite or remove one of the default
The severity value must be nonnegative.
Upon success, the value
Upon error, the return value is
Possible errors include: out of memory, attempt to remove a
nonexistent or default severity class.
is provided in glibc since version 2.1.
This function is not specified in the X/Open Portability Guide
It is available on System V
New severity classes can also be added by setting the environment variable