Record Addition in multiple key access settings
When a secondary index is used, adding a record involves updating the data file, the primary index and the secondary index. The secondary index update is similar to the primary index update.
Secondary keys are entered in canonical form (all capitals). The upper- and lower- case form must be obtained from the data file. As well, because of the length restriction on keys, secondary keys may sometimes be truncated.
The secondary index may contain duplicate (the primary index couldn’t).