true Cmaj7 chord ?

[joelinux]

I would like to be able to write a true Cmaj7 chord.  This is a I
chord in the key of C major with an added scale tone 7th.  There is no such
chord as a Cadd(#7) which is spelled out in the Lilypond documentation  examples
as c e g b.  A #7 in
the key of C would be another C an octive above the root.  A C7 chord does not
belong to the key of C at all. It is a V7 chord in the Key of F.

http://www.lilypond.org/doc/v2.8/Documentation/user/lilypond/Chord-name-chart.html#Chord-name-chart

By the way the .ly file of this documentation page won't run in 2.8.5