We describe a multiplicative normal form for rational functions
which exhibits the shift structure of the factors.
Using this normal form we construct a minimal representation of
hypergeometric terms in one variable. Our main result concerns
hypergeometric terms in two variables: every such term is the quotient
of a proper term by a polynomial. This may open the way to prove a
conjecture of Wilf and Zeilberger which states that a hypergeometric
term is proper if and only if it is holonomic.
