The CDF_ATTCREATE function creates a new attribute in the specified Common Data Format file. If successful, the attribute ID is returned.
            Examples
            id = CDF_OPEN('test') 
            xx = CDF_ATTCREATE(id, 'Attribute-1', /GLOBAL_SCOPE)
            CDF_ATTRENAME, id, 'Attribute-1', 'My Favorite Attribute'
            PRINT, CDF_ATTNUM(id, 'My Favorite Attribute')
            CDF_CLOSE, id 
            Syntax
            Result = CDF_ATTCREATE( Id, Attribute_Name [, /GLOBAL_SCOPE] [, /VARIABLE_SCOPE] )
            Return Value
            Returns the attribute ID.
            Arguments
            Id
            The CDF ID of the file for which a new attribute is created, returned from a previous call to CDF_OPEN or CDF_CREATE.
            Attribute_Name
            A string containing the name of the attribute to be created.
            Keywords
            GLOBAL_SCOPE
            Set this keyword to make the scope of the attribute global. This is the default.
            VARIABLE_SCOPE
            Set this keyword to indicate that the attribute’s scope is per variable.
            Version History