1\version "2.16.0"
2\header {
3    texidoc = "The layout of the major 7 can be tuned with
4@code{majorSevenSymbol}.  It does not break if @code{majorSevenSymbol} is unset.
5One should see: triangle - j7 - triangle - #7."
6}
7
8\chords {
9    c:7+
10    \set majorSevenSymbol = \markup { "j7" }
11    c:7+
12    \unset majorSevenSymbol
13    c:7+
14    \unset Score.majorSevenSymbol
15    c:7+
16}
17