+;;
+;; URL: http://www.dsmit.com/lisp/
+;;
+;; The whitespace library is intended to find and help fix five different types
+;; of whitespace problems that commonly exist in source code.
+;;
+;; 1. Leading space (empty lines at the top of a file).
+;; 2. Trailing space (empty lines at the end of a file).
+;; 3. Indentation space (8 or more spaces at beginning of line, that should be
+;; replaced with TABS).
+;; 4. Spaces followed by a TAB. (Almost always, we never want that).
+;; 5. Spaces or TABS at the end of a line.
+;;
+;; Whitespace errors are reported in a buffer, and on the modeline.
+;;
+;; Modeline will show a W:<x>!<y> to denote a particular type of whitespace,
+;; where `x' and `y' can be one (or more) of:
+;;
+;; e - End-of-Line whitespace.
+;; i - Indentation whitespace.
+;; l - Leading whitespace.
+;; s - Space followed by Tab.
+;; t - Trailing whitespace.
+;;
+;; If any of the whitespace checks is turned off, the modeline will display a
+;; !<y>.
+;;
+;; (since (3) is the most controversial one, here is the rationale: Most
+;; terminal drivers and printer drivers have TAB configured or even
+;; hardcoded to be 8 spaces. (Some of them allow configuration, but almost
+;; always they default to 8.)
+;;
+;; Changing `tab-width' to other than 8 and editing will cause your code to
+;; look different from within Emacs, and say, if you cat it or more it, or
+;; even print it.
+;;
+;; Almost all the popular programming modes let you define an offset (like
+;; c-basic-offset or perl-indent-level) to configure the offset, so you
+;; should never have to set your `tab-width' to be other than 8 in all
+;; these modes. In fact, with an indent level of say, 4, 2 TABS will cause
+;; Emacs to replace your 8 spaces with one \t (try it). If vi users in
+;; your office complain, tell them to use vim, which distinguishes between
+;; tabstop and shiftwidth (vi equivalent of our offsets), and also ask them
+;; to set smarttab.)
+;;
+;; All the above have caused (and will cause) unwanted codeline integration and
+;; merge problems.
+;;
+;; whitespace.el will complain if it detects whitespaces on opening a file, and
+;; warn you on closing a file also (in case you had inserted any
+;; whitespaces during the process of your editing).
+;;