"Music expressions" and "Music classes" in Internals Reference

[Carl D. Sorensen]

I'd like some clarification on some terms in the Internals Reference.

Section 1. Music definitions has three subsections:  1.1 Music expressions,
1.2 Music classes, and 1.3 Music properties

The title "Music expressions" is followed by the description string "Objects
that represent music"
"Music classes" has no description string
"Music properties" has the description string "All music properties,
including descriptions".

These titles are confusing to me.

I'd recommend changing "Music expressions" to "Music objects".  In my mind,
a music expression is defined as a construct in a LilyPond input file.  The
things we are seeing in section 1.1 do not appear in LilyPond input files.

I'd recommend changing "Music classes" to "Music types", with a description
string "Types of music objects, used to determine the engravers used".  I
prefer the name "type" to "class", because the music property you look up to
get the one of these items is 'type, IIUC.

I'd recommend changing the description string for "Music properties" to
"Properties of music objects, which control how the objects are handled by
engravers"

Also, I'd recommend that sections 1.2 and 1.3 be switched, because Music
expressions have properties, and one of the properties is 'type, which is
explained in Music types.

Any comments?

Thanks,

Carl