’th extension in an NDF. If the requested extension does not exist, then the name is returned blank. The routine may therefore be used to obtain the names of all the extensions present by setting N to 1,2... etc. until a blank name is returned. Note that the order in which these names are obtained is not defined.
The symbolic constant NDF__SZXNM is provided to define the length of character variables which are to hold an NDF extension name. This constant is defined in the include file NDF_PAR.