doc clarification

[catalaco -]

The last paragraph of 1.2.2 LilyPond 
variables<http://lilypond.org/doc/v2.18/Documentation/extending/lilypond-variables>
 in Extending 
LilyPond<http://lilypond.org/doc/v2.18/Documentation/extending/index> is very 
hard to understand.
The whole thing might need to be rewritten but I don't understand enough to do 
that. All I can do is offer suggestions for rephrasing, although I might be 
misinterpreting as I'm not fully understanding what I'm reading!

Original text
-------
The usual way to refer to Lilypond variables, LilyPond Scheme 
syntax<http://lilypond.org/doc/v2.18/Documentation/extending/lilypond-scheme-syntax>,
 is to call them using a backslash, i.e., \twentyFour.
Since this creates a copy of the value for most of LilyPond’s internal types, 
in particular music expressions, music functions don’t usually create copies of 
material they change. For this reason, music expressions given with # should 
usually not contain material that is not either created from scratch or 
explicitly copied rather than directly referenced.
-------


Rephrased
-------
Lilypond variables are usually called using a backslash, e.g. \twentyFour (see 
LilyPond Scheme 
syntax<http://lilypond.org/doc/v2.18/Documentation/extending/lilypond-scheme-syntax>),
 which creates a copy of the value. For that reason music functions in LilyPond 
don't usually create copies of material they change. Because of this, scheme 
music expressions written with the # syntax should not directly reference 
material. They should only be used for material created from scratch or 
explicitly copied.
-------

Greetings,
Martin