| isfd | isam file identifier |
| data | image of record to be updated |
SUCCESS, or a negative value on error, in which case the error code is found in iserrno.
the record to be updated is determined by the contents of the primary index fields as found in the data image passed.
if the primary index allows duplicates this call will fail.
the contents of the current record in the data file will be replaced with the image passed, and all related indexes updated.