The second (CLIST) argument to NDF_PROP specifies a list of components and extensions which are to have their values propagated (i.e. copied) to initialise the new NDF. The default (blank) value specified above causes all extensions, together with the title, label and history components to be propagated, if present. These three standard components are considered ``safe'', in that they are likely to retain their validity through most common types of processing which takes place on NDFs.
Note, however, that no axis, data, variance, quality
or units information will be propagated by default.
This allows an application to explicitly process these components to
generate new versions for the output structure if possible, or simply to
ignore them and have them omitted from the output NDF if the necessary
processing cannot be performed.