( x_n ... x₁ n -- flag )

Attempt to restore the input source specification to the state described by x₁ through x_n. flag is true if the input source specification cannot be so restored.

An ambiguous condition exists if the input source represented by the arguments is not the same as the current input source.

15.6.2.1908 N>R, 15.6.2.1940 NR>, A.6.2.2182 SAVE-INPUT.