  A survey of direct and inverse type results for row sequences of Pad\'e and
Hermite-Pad\'e approximation is given. A conjecture is posed on an inverse type
result for type II Hermite-Pad\'e approximation when it is known that the
sequence of common denominators of the approximating vector rational functions
has a limit. Some inverse type results are proved for the so called incomplete
Pad\'e approximants which may lead to the proof of the conjecture and the
connection is discussed.
