(
i * x c-addr u --
j * x )
Save the current input source specification. Store minus-one
(-1) in
SOURCE-ID if it is present. Make the string
described by
c-addr and
u both the input source
and input buffer, set
>IN to zero, and interpret. When
the parse area is empty, restore the prior input source
specification. Other stack effects are due to the words
EVALUATEd.