Documentation error: Sign element

[Evan Brooks]

The online documentation for the sign element at:

http://www.finalemusic.com/UserManuals/ ... L-sign.htm

shows an F Clef in its normal position, with the MusicXML code for it being:

<Clef>
<Sign>F</Sign>
<Line>2</Line>
</Clef>

However, it should actually say:

<Clef>
<Sign>F</Sign>
<Line>4</Line>
</Clef>

as described in the staff-line description in:

http://www.finalemusic.com/UserManuals/ ... L-clef.htm

"Line numbers are counted from the bottom of the staff. Standard values are 2 for the G sign (treble clef), 4 for the F sign (bass clef), 3 for the C sign (alto clef) and 5 for TAB (on a 6-line staff)."

I would also suggest that the documentation include a description of where to place a clef in the absence of a line-number element. It could state that the clef should be centered within the staff, or that it should go in the clef's "traditional" position, although that could leave things open to more interpretation than is desired.

[Evan Brooks]

After some thought, it appears that the clef line element documentation needs even further clarification. For example:

(1) The default clef line for a TAB clef on a 6-line staff is 5. Why is this? Does this mean that the default clef line for a TAB clef on a 4-line staff (for a 4-stringed instrument) is 3, or that the clef line for a TAB clef on a n-line staff is n-1 in general?

(2) The current documentation shows that the Percussion clef does not come with a line element. But the DTD allows one, so what happens if it has one? What is the "default" line element that a Percussion clef would have if it was to be printed centered within the staff, whatever the staff size was?

(3) What is the proper position on the staff for ANY clef when it is defined WITHOUT a line element? Each clef should have a default position it is drawn in on the staff if no line element is present, as well as what value of line element would also provide that same default position if it was in fact provided. Clefs that are intended to be centered on a staff as a default, such as C, TAB and Percussion, should be specified as "centered vertically", rather than attached to a particular staff line, because the given staff might not have that many lines. Think of a 1-line percussion staff, for example.

[Michael Good]

Hi Evan,

Thanks for pointing out the documentation error for the F clef. I'll send this on to our writer so we can get that fixed.

In practice I expect that most software ignores the line element for the TAB and percussion clefs when reading a MusicXML file. In the next version of MusicXML we can figure out if there are ways to address these issues that clarify clef interchange without breaking things in the way that current applications work.

I would probably group C clef with F and G clefs in terms of their treatment since many line positions are possible with very different semantics - and in the case of C clef, at least 2 different line values are in pretty common use.