Question about 'back quote' in scheme markups within Documentation examples

[James Lowe]

Hello,

Going on from the 'curly quotes' problem that was resolved a couple of
days back in our documentation, I noticed in the NR while scanning
through another 'odd' single quote mark after the hash (#) character.

\override #`(direction . ,UP)

instead of

\override #'(direction . ,UP)

See attached screenshot for an example

An example is from the the NR Appendix, 'A.8.2 Align'

http://lilypond.org/doc/v2.13///Documentation/notation/align

specifically '\dir-column args (markup list)'

I wondered if anyone can tell me if this is a mistake or what the
significance of the back-quote is vs the standard singe quote?

James