Question_about CapsAndNames andDelimitersAndEscapes for-lilypond-items

[Eyolf Ostrem]

One of the things that has taken me the longest time to get my head around in 
LP, and where I have made most mistakes with typos that I haven't understood 
why they don't work, is the various combinations of CamelCase, 
scheme-type-hyphenated-names, camelCaseWithLowercaseFirstLetter, and the 
various one-word versions of these, which result in equal-looking names.
Furthermore, which naming schemes are REQUIRED in the various languages that 
are involved and which are only conventions (in the manual, e.g.).
And, thirdly, which items are escaped with \ and which are not.
I've looked through the documentation, and then one gets a fairly clear 
picture, but it would have been nice to have it summarized in one place in 
the manual.
The patterns seem to be (but correct me if I'm wrong):

Music expressions, GROBs and Contexts: CamelCase
Music classes, music properties, Grob interfaces, and backend properties: 
scheme-type
Engravers: Caps_and_underscores
Context properties: lowercaseAndCamelCase
backend properties: scheme-style (but X and Y are capitalized as first items!)
scheme functions: ly:plus-scheme-style

This results in the following variants for various bar-related commands:

Bar_engraver
barCheckSynchronize
BarLine

That's clear enough, I suppose. I still don't have a consistent understanding 
of the difference between music properties and context properties, and why 
they need different style, but I'll get there.

But there's more: in one place in the manual, there is an example where both  
\consists Bar_engraver and 
\consists "Volta_engraver"
appear. Why the quotation marks? Is this optional? In general? or is it a 
typo?
Why \Score in some cases and \score in others? Is that optional? Or are they 
in fact different types of names?

And the following, which I simply don't understand:

"9.1.5 Changing context default settings

      \layout {
        ...
        \context {
           \Staff
                ...
        }
      }
   Here      \Staff takes the existing definition for context Staff from the 
identifier \Staff."

Why is this an identifier, which usually (it seems) are lower-case? Why isn't 
what follows it enclosed in {}? And, again, do the three "Staff"s in the 
explaining sentence refer to three different (types of) objects? Is the first 
\Staff a different item than the context Staff, which just happens to have 
the same name? Is this \Staff the "identifier \Staff" which is mentioned 
later in the sentence, or is it yet another thing with the same name?
I'm confused... Mostly because of the {}-less syntax, but also by the 
same-same-but-different names. 
Can someone enlighten me?

I feel that the documentation in many cases either gives simple examples 
(where it is not evident what are simply randomly chosen names in the 
examples and what is LP functions), or - in the program reference - is 
extremely terse. The middle ground, which would connect the two, is often 
missing, such as in the case of the naming conventions/rules.