Chords and what they mean

[70147persson]

First I will declare, that I am not 100 percent sure this is a bug, but 
friends of mine, musicians, say it probably is. Also, as I am not an 
expert, I have tried to learn by searching on among others Wikipedia.

It is about chords, a few of them. It started when I should clean write 
a score from a manuscript. In one measure there were noted two chords, 
C5 and C. Obviously not the same, as they stood just beside of each 
other. A search on Wikipedia also told me, and this was also confirmed, 
the author's intention, that C5 means C(no 3), hence <c g>, while the 
chord C means <c e g>. But LilyPond treats these two the same and 
produces the same notes. This is also clearly said e.g. in Appendices 
A.1 and A.2 of Notation Reference, as well as in the text part. However 
even if possibly a correct procedure, is it a correct practise?

Another such discrepancy is about Csus, which Wikipedia (and my friends) 
says is equivalent to Csus4, hence <c f g>. But LilyPond produces <c g>, 
hence what should come from the notation C5 as in the previous paragraph.

So, what is the truth?
Kaj