search string to a regular expression specified by the variable
@code{search-whitespace-regexp}. For example, to make spaces match
sequences of newlines as well as spaces, set it to
-@samp{"[[:space:]\n]+"}. The default value of this variable depends
-on the buffer's major mode; most major modes classify spaces, tabs,
-and formfeed characters as whitespace.
+@samp{"[[:space:]\n]+"}. The default value of this variable considers
+any sequence of spaces and tab characters as whitespace.
If you want whitespace characters to match exactly, you can turn lax
space matching off by typing @kbd{M-s @key{SPC}}