The routine reads a scalar value from a component within a named NDF extension. The extension must already exist, although the component within the extension need not exist (a default value, established beforehand, will be returned if necessary).

CALL NDF_XGT0x( INDF, XNAME, CMPT, VALUE, STATUS )

INDF = INTEGER (Given)

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

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

VALUE = ? (Given and Returned)

STATUS = INTEGER (Given and Returned)

• There is a routine for reading values with each of the standard Fortran data types: integer, real, double precision, logical and character. Replace the (lower case) "x" in the routine name by I, R, D, L or C as appropriate.

• The value given for the CMPT argument may be an HDS path name, consisting of several fields separated by ’.’, so that an object can be accessed in a sub-component (or a sub-sub-component...) of an NDF extension. Array subscripts may also be included. Thus a string such as ’CALIB.FILTER(3).WAVELENGTH’ could be used as a valid CMPT value.

• If the requested component in the extension does not exist, then the VALUE argument will be returned unchanged. A suitable default should therefore be established before this routine is called.

• If the length of the character VALUE argument passed to the NDF_XGT0C routine is too short to accommodate the returned result without losing significant (non-blank) trailing characters, then this will be indicated by an appended ellipsis, i.e. ’...’. No error will result.