Load Employee Data (%WPR999REMP) lets you load to the Employee table and a couple of employee child tables:
pr_ni is the NI details tables used in UK, Isle of Man, Jersey and Guernsey only.
co_controlTaxCert is a use of the co_control table for Ireland tax certificates.
The first line in the load file gives the table to load to (as mentioned above), or will be assumed to be the Employee table if omitted.
The next line gives the fields for that table. These are as seen in the Database Enquiry and can include extended fields and RW fields.
Then the subsequent lines give the field values. If an existing record can be found for the key fields included on each line this record is updated. If no existing record can be found a new record is created.