Open an existing container file for reading, writing or updating and return a primary locator to the top-level object. If the file is currently open in the specified mode, the routine increments the reference count rather than re-opening the file.

CALL HDS_OPEN( FILE, MODE, LOC, STATUS )

FILE = CHARACTER $\ast$ ( $\ast$ ) (Given)

MODE = CHARACTER $\ast$ ( DAT__SZMOD ) (Given)

LOC = CHARACTER $\ast$ ( DAT__SZLOC ) (Returned)

STATUS = INTEGER (Given and Returned)

If a file extension is not specified, ‘.sdf’ is used. If the top-level object is a structure array, loc will be associated with the complete array, not the first cell. Thus, access to any of the structure’s components can only be made through another locator which is explicitly associated with an individual cell (see DAT_CELL).