A status code is returned from most CDF functions. The cdf.h (for C) and CDF.INC (for Fortran) include files contain the numerical values (constants) for each of the status codes (and for any other constants referred to in the explanations). The CDF library Standard Interface functions CDFerror (for C) and CDF_error (for Fortran) can be used within a program to inquire the explanation text for a given status code. The Internal Interface can also be used to inquire explanation text.
There are three classes of status codes: informational, warning, and error. The purpose of each is as follows:
Indicates success but provides some additional information that may be of interest to an application.
Indicates that the function completed but possibly not as expected.
Indicates that a fatal error occurred and the function aborted.
Status codes fall into classes as follows:
Error codes < CDF_WARN < Warning codes < CDF_OK < Informational codes
CDF_OK indicates an unqualified success (it should be the most commonly returned status code). CDF_WARN is simply used to distinguish between warning and error status codes.