When is a record NULL?

["David E. Wheeler" <david(at)kineticode(dot)com>]

How can a record be neither NULL or NOT NULL?

    try=# select ROW(1, NULL) IS NULL;
     ?column?
    ----------
     f
    (1 row)

    try=# select ROW(1, NULL) IS NOT NULL;
     ?column?
    ----------
     f
    (1 row)

This makes it rather hard to tell, in PL/pgSQL, when I've fetched the  
last record from a cursor…

Best,

David