"Evaluate FORM in PROCESS, which form must be printable.
Form should evaluate to a value that must be printable, or
signal an error. Value is (ok . VALUE) if no error was
-signaled, or (error . VALUE) otherwise. If RAW, instruct
-PROCESS not to attempt to decode the printed representation of
-FORM as multibyte text; this does not influence the decoding
-whatever value it returns.
+signaled, or (error . VALUE) otherwise. It may also be (exit
+. BACKTRACE) if Emacs exited whilst FORM was executing. If RAW,
+instruct PROCESS not to attempt to decode the printed
+representation of FORM as multibyte text; this does not
+influence the decoding whatever value it returns.
Set AS-PRINTED to insist that the value be returned as a string;
this enables non-printable values to be returned in a meaningful