MARENLAM does not perform a logical check. Not all fields of the reservation file need be assigned a value.
Modifying entry records
The fields of the entry record are write-protected. Entries that are to be modified first have to be selected by entering “X” or “/” in the selection column. The paging function can be used to page through the entries.
A selection is confirmed by pressing 
. Following that, the modify function is called by pressing the 
key or by entering the control statement MODIFY and pressing 
.
The fields of the selected entries can now be modified. When all modifications have been made, the entries are protected again against overwriting by pressing 
.
If the reservation file is just being created (option New in the File menu) the work area contains 3 “empty” entries. The entries can be modified immediately. They only have to be selected first, if the 
key has already been pressed or if another function has already been called.
Inserting entry records
In order to insert a new entry record above or below of an existing entry, the existing entry must be selected first in the selection column. Several positions can be selected simultaneously for new records to be inserted.
The following selections are available:
“X” or “/” means that the new entry is inserted above the selected entry.
“A” means that the new entry is inserted below the selected entry.
A selection is confirmed by pressing 
. Following that, the insert function is called by pressing the 
key or by entering the control statement INSERT and pressing 
.
The new entries are initially empty. They can now be modified. When all modifications have been made, the entries are protected again against overwriting by pressing 
.
Deleting entry records
Entries that are to be deleted must first be selected with “X” or “/”. The paging function can be used to page through the entries.
A selection is confirmed by pressing 
. Following that, the delete function is called by pressing the 
key or by entering the control statement ERASE and pressing 
.
After that the selected entries are no longer available. They cannot be undeleted. Entries that were deleted by mistake can be reconstructed by recovering the status of the last backup of the reservation file (via the File menu and then option Open).