This invokes a graphical utility to inspect the catalog. Requirements are such as:
 
The window has two panes, one for a catalog tree, and one for information about the actual node.
 
The catalog is expanded, that is all <ablock>s are replaced by the referenced contents.
 
It is possible to display the attributes of an ablock, the metadata or to invoke a tool displaying the contents of the referenced <file>.
Perhaps the other routines mentioned above can be invoked from this tool also.