Re: Add warning about using \relative with tagged music (3253) (issue 7798045)

[k-ohara5a5a]

I'm confused by the new text.  I also fail to see the motivation for
explaining this; no-one has reported any confusion with the behavior.

You might just say
"Notice that \keepWithTag can change the pitches used as reference for
later pitches written using relative input mode.  The d below is
interpreted as a fourth below g' or as a third below f'' depending on
which tag is kept:
 music = << \tag #'score a \tag #'part f >>
 \relative c'' { c \keepWithTag #'score \music d}
Applying \relative first, then \keepWithTag is the usual method of
input, so that \relative acts on the pitches as-input:
 \keepWithTag #'score \relative c'' { c \music d}
"


https://codereview.appspot.com/7798045/diff/1/Documentation/notation/input.itely
File Documentation/notation/input.itely (right):

https://codereview.appspot.com/7798045/diff/1/Documentation/notation/input.itely#newcode2236
Documentation/notation/input.itely:2236: to notes with pitches expressed
in absolute notation.  If music is
This makes it sound like I cannot do this:

music = \relative c' \new Staff{
  << \tag#'F {f} \tag#'G {g} >>
  c }  % C in relative notation is a fourth above the G
\keepWithTag#'F \music
\keepWithTag#'G \music

https://codereview.appspot.com/7798045/diff/1/Documentation/notation/input.itely#newcode2239
Documentation/notation/input.itely:2239: absolute notation before being
filtered with @code{\keepWithTag} or
I would not think that \relative converted pitches to absolute notation.
 The computer has already read my relative-pitch input notation, and I
have no concept of a 'notation'  at that point.  I suppose
\displayLilyMusic does recreate absolute notation.

https://codereview.appspot.com/7798045/