cast support function

If the source and target data types of a cast do not have the same binary representation, the database server calls a C function to perform the conversion. If the two types have the same binary representation, a C function is not needed.

A cast support function is an internal database server function; the user never calls this function directly from SQL.

For more information about creating cast support functions, see the HCL Informix® User-Defined Routines and Data Types Developer's Guide.