InterBase Error Codes
InterBase error codes have two uses. First, they are used internally by InterBase functions to build and display descriptive error message strings. For example,
isc_interprete() calls another function which uses the InterBase error code to retrieve a base error message from which it builds an error message string you can display or store in a log file.
Secondly, when you write your own error-handling routine, you can examine the status vector directly, trapping for and reacting to specific InterBase error codes.
When the second long of a cluster is an InterBase error code, then subsequent clusters may contain additional parameters for the error message string associated with the error code. For example, a generic InterBase error message may contain a replaceable string parameter for the name of the table where an error occurs, or it may contain a replaceable numeric parameter for the code of the trigger which trapped the error condition.
If you write your own parsing routines, you may need to examine and use these additional clusters of error information.