  The purposes and possibilities of future diffractive structure function
measurements at HERA are presented. A review of the current range and accuracy
of the measurement of $F_2^{D(3)}(\beta, x_p, Q^2)$ is presented and an
estimate of the precision of future measurements is given. A feasibility study
is performed on the measurement of the structure functions $F_2^{D(4)}(\beta,
x_p, Q^2, t)$, $F_{2 charm}^{D}$, $R^{D(3)}$, $R^{D(4)}$ and $F_L^{p}$.
Included in this study are estimates of the integrated luminosity required, the
analysis techniques to be employed and values of systematic error that could be
expected.
