Obviously the Agatha Christie novel
<a class="postlink" href="http://en.wikipedia.org/wiki/N_or_M%3F#cite_note-3" onclick="window.open(this.href);return false;">http://en.wikipedia.org/wiki/N_or_M%3F#cite_note-3</a>
title based on
A CATECHISM
FROM THE BOOK OF COMMON PRAYER, 1549,ENLARGED, 1637, REVISED IN THE BISHOP WHITE BOOK, 1785,
Parents are exhorted to teach this Catechism to their Children, and Ministers to instruct and examine Candidates for Confirmation in the same.
QUESTION. What is your Christian name?
Answer. N., or, M.
Question. When did you receive this name?
Answer. At my Baptism, when I was dedicated to God, and received into the visible Church of Christ.
<a class="postlink" href="http://www.stlukesrec.org/bcp1963/catechism63.pdf" onclick="window.open(this.href);return false;">http://www.stlukesrec.org/bcp1963/catechism63.pdf</a>