-The optional fifth argument SUBEXP specifies a subexpression of the match.\n\
-It says to replace just that subexpression instead of the whole match.\n\
-This is useful only after a regular expression search or match\n\
+The optional fifth argument SUBEXP specifies a subexpression;\n\
+it says to replace just that subexpression with NEWTEXT,\n\
+rather than replacing the entire matched text.\n\
+This is, in a vague sense, the inverse of using `\\N' in NEWTEXT;\n\
+`\\N' copies subexp N into NEWTEXT, but using N as SUBEXP puts\n\
+NEWTEXT in place of subexp N.\n\
+This is useful only after a regular expression search or match,\n\