Single quotes as special characters in elisp regex

Question

(defun string-is-capitalized (str)
  (let ((case-fold-search nil))
    (string-match-p "\\`[A-Z]*\\'" str)))

in the above regex, what does the single quotes backward & forward ` & ' do? i don't see it as a special code in gnu page, http://www.gnu.org/software/emacs/manual/html_node/elisp/Regexp-Special.html

Answer 1

The backslash-backtick \` matches the empty string only at the front of the string or buffer being matched, while backslash-single-quote \' matches the empty string only at the end of the string or buffer being matched. You can find them documented in the Regexp Backlash documentation.