Variable: whitespace-bob-marker
whitespace-bob-marker is a buffer-local variable defined in
whitespace.el.gz.
Documentation
Position of the buffer's first non-empty line.
This marker is positioned at the beginning of the first line in
the buffer that contains a non-space character. If no such line
exists, this is positioned at the end of the buffer (which could
be after whitespace-eob-marker if the buffer contains nothing
but empty lines).
Source Code
;; Defined in /usr/src/emacs/lisp/whitespace.el.gz
(defvar-local whitespace-bob-marker nil
"Position of the buffer's first non-empty line.
This marker is positioned at the beginning of the first line in
the buffer that contains a non-space character. If no such line
exists, this is positioned at the end of the buffer (which could
be after `whitespace-eob-marker' if the buffer contains nothing
but empty lines).")