whitespace-big-indent-regexp

whitespace-big-indent-regexp is a variable defined in `whitespace.el'.
Its value is

"^\\(\\(?:	\\{4,\\}\\| \\{32,\\}\\)[	 ]*\\)"

Documentation:
Specify big indentation regexp.

If you're using `mule' package, there may be other characters
besides "\t" that should be considered TAB.

NOTE: Enclose always by \\( and \\) the elements to highlight.
Use exactly one pair of enclosing \\( and \\).

Used when `whitespace-style' includes `big-indent'.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 25.1 of Emacs.