Variable: whitespace-tab-regexp
whitespace-tab-regexp is a customizable variable defined in
whitespace.el.gz.
Value
"\\( +\\)"
Documentation
Specify TAB characters regexp.
If you're using mule package, there may be other characters
besides "\\t" that should be considered TAB.
Here are some examples:
"\\\\(^\\t+\\\\)" visualize only leading TABs.
"\\\\(\\t+$\\\\)" visualize only trailing TABs.
"\\\\(^\\t+\\\\|\\t+$\\\\)" visualize leading and/or trailing TABs.
" \\\\(\\t+\\\\) " visualize only TABs between SPACEs.
NOTE: Enclose always by \\( and \\) the elements to highlight.
Use exactly one pair of enclosing \\( and \\).
Used when whitespace-style includes tabs.
Source Code
;; Defined in /usr/src/emacs/lisp/whitespace.el.gz
(defcustom whitespace-tab-regexp "\\(\t+\\)"
"Specify TAB characters regexp.
If you're using `mule' package, there may be other characters
besides \"\\t\" that should be considered TAB.
Here are some examples:
\"\\\\(^\\t+\\\\)\" visualize only leading TABs.
\"\\\\(\\t+$\\\\)\" visualize only trailing TABs.
\"\\\\(^\\t+\\\\|\\t+$\\\\)\" \
visualize leading and/or trailing TABs.
\" \\\\(\\t+\\\\) \" visualize only TABs between SPACEs.
NOTE: Enclose always by \\\\( and \\\\) the elements to highlight.
Use exactly one pair of enclosing \\\\( and \\\\).
Used when `whitespace-style' includes `tabs'."
:type '(regexp :tag "TAB Chars")
:group 'whitespace)