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Copying NDFs  

Placeholders also play a role in the copying of NDF data structures from one location to another within the data system. In this case they are used to identify the destination for the copying operation, which is performed by the routine NDF_COPY. This should be preceded by a call which generates a suitable placeholder. For instance:

      CALL NDF_PLACE( LOC, 'MY_NDF_COPY', PLACE, STATUS )
      CALL NDF_COPY( INDF1, PLACE, INDF2, STATUS )

Here, the placeholder causes NDF_COPY to copy the NDF with identifier INDF1 to form a new NDF in the component MY_NDF_COPY of the HDS structure with locator LOC. As usual, the placeholder is annulled by the copying operation and a new NDF identifier INDF2 is issued to refer to the new data structure. This new structure contains all the information which was present in the original. It is possible to copy both base NDFs and NDF sections in this way, but the copying operation always creates a new base NDF.

Naturally, it is also possible to create a temporary copy of an NDF by using NDF_TEMP to obtain the placeholder, as follows:

      CALL NDF_TEMP( PLACE, STATUS )
      CALL NDF_COPY( INDF1, PLACE, INDF2, STATUS )



next up previous
Next: Selective Copying of NDF Components
Up: CONNECTING WITH THE DATA SYSTEM
Previous: Temporary NDFs


Starlink User Note 33
R.F. Warren-Smith
11th January 2000
E-mail:rfws@star.rl.ac.uk

Copyright © 2000 Council for the Central Laboratory of the Research Councils