[David O. McKay Presidency]
... With the thought in mind of reducing the time spent by bishops, branch presidents and mission presidents in preparing recommends for members of the Church who desire to go to one or more temples, a recommend form has been prepared which may be used for any and all temples. Hereafter, one recommend acceptable in any temple will be issued to each patron rather than issuing a separate recommend for each temple.
[Source: David O. McKay, Henry D. Moyle, and Hugh B. Brown, circular letter, May 29, 1963, in Anderson, Devery; The Development of LDS Temple Worship, 1846-2000: A Documentary History, http://amzn.to/TempleWorship]