To allow deletion of object from the database based upon a user specified key vector HEPDB provides the user callable routine CDPURK. Once again as in the call to CDSTOR discussed earlier the user sets up a key vector of size enough to hold all system, special user, validity and normal user keys and fills in the required elements for the envisaged deletion. The user then creates another vector (in our example to follow it is called IMASK ) which acts as a mask specifying which elements of our key vector are to be considered in the deletion operation (this is set by the element taking a non-zero value).
Note also that the routine CDPURK can be used to `undelete' previously deleted objects. The specification of the object to be restored is the same as that of deleting an object. To perform the undelete operation the user simply specifies character option 'U'.