One final consideration may apply if multiple applications are to be invoked from a single program (as in the example in §) but some ``global'' NDF data structures are required to remain in use between applications. This is not a common requirement, but since default history recording is normally initiated only by the action of releasing an NDF, it will not occur in such a situation, so the global datasets will not automatically receive history information. To overcome this problem, a call to NDF_HEND may be used at the end of each application, as follows:
CALL NDF_HEND( STATUS )
This notifies the NDF_ system that the current application has finished. It causes default history information to be written, if required, to all NDFs currently in use and ensures that new history records will be created to contain any history information written subsequently (i.e. by the next application). NDF_HEND then revokes any ``current application'' name established via the NDF_HAPPN routine (see §).
If its STATUS argument indicates an error condition, NDF_HEND also records the STATUS value and pending error message information in any suitable history components belonging to NDFs currently in use, as described in §.