The missing portions of variables subjected to SPLINE or MSPLINE transformations are handled the same way as for OPSCORE, MONOTONE, UNTIE, and LINEAR transformations (see the previous section). The ...

Predicted Values for the Monotone Regression Function---; proc transreg data=A; title2 'A Monotone Regression Function'; model identity(Y)=mspline(X / nknots=9); output out=A pprefix=M; id X1-X4 LY; ...