Re: lilypond/Documentation/user examples.itely

[Juergen Reuter]

On Fri, 7 Jan 2005, Mats Bengtsson wrote:

> ...
> 
> Now I realize that you did this to get an example of how to use \tag.
> Still, the problem is that it doesn't really show any advantage (as
> far as I can see). Can't we find a better example where the command
> gives a clearer advantage?
> 
>     /Mats
> 

One of the original reasons for which I requested and proposed the \tag 
feature was to tag different editions (or versions) of the same piece, 
e.g. autograph X, manuscript Y, Urtext Z, etc.  The idea was to handle 
(and possibly comment on) multiple editions in the same file and, ideally, 
in the same place of that file.  In the \score block, you just would 
select the edition you wanted to print (or a combination of editions, e.g. 
if only a fragment of autograph X has survived, then use the autograph 
where possible, and use the manuscript as a fallback elsewhere; but this 
mechanism would, afaics, require extending the \keepWithTag feature).

Another requested feature at that time was the cue notes problem: You want 
to print cue notes only when extracting parts, but not when printing the 
whole score.  Hence, just tag all cue notes and filter them out when 
printing the whole score.

For more details, see the \tag discussion thread in August 2003:
http://lists.gnu.org/archive/html/lilypond-devel/2003-08/msg00099.html

Generally speaking, the \tag feature is useful to tag *subsets* of those 
music expressions that you want to put into your \score block (i.e. 
subsets of, typically, staff or voice level grained music expressions).  
Otherwise, as you correctly point out, you could select the right music 
directly in the score block rather than requiring the \tag feature.

Greetings,
Jürgen