SDDS_target: Address of SDDS_TABLE structure into which to copy data.
SDDS_source: Address of SDDS_TABLE structure from which to copy data.
filename: A NULL-terminated character string giving a filename to be associated with
the new SDDS_TABLE. Typically, the name of a file to which the copied data will be
written after modification. Ignored if NULL.
filemode: A NULL-terminated character string giving the fopen file mode to be used
to open the file named by filename. Ignored if filename is NULL.
return value: Returns 1 on success. On failure, returns 0 and records an error message.