• 03.042 “Moon-letters are rune-letters,

Well, well, well.  This very line is one of the samples of how this word-phrase is used, so I could give it the JRRT tag, but the earlier example also has the hyphen and I think that’s where the line is drawn.

rune letter  n.

1852   Gentleman’s Mag. May 475/1   One distinctive mark of Northernism is the sound th (þ, ð); another is the sound w (ƿ), both originally represented by Rune-letters unknown to the Latin alphabet.

The etymology given in OED, by the way, is really quite funny.  Could be Icelandic… or Latin…

“rune, n.2.” OED Online, Oxford University Press, June 2017, http://www.oed.com/view/Entry/168900. Accessed 19 September 2017.