Double-G clefs sound one octave lower, so do not combine with dis/ dis.place/clef.dis/clef.dis.place. In some cases the double G clef may be used to indicate that two voices share one staff and does not sound one octave lower. In this case the oct attribute may be used to clarify the sounding octave of the instruments for the clef.
<macroSpec ident="data.CLEFSHAPE" module="MEI" type="dt">
<desc xml:lang="en">Clef shape attribute values (Read, p.53-56). Some values correspond to the Unicode
Standard.</desc>
<content>
<valList type="closed">
<valItem ident="G">
<desc xml:lang="en">G clef (Unicode 1D11E).</desc>
</valItem>
<valItem ident="GG">
<desc xml:lang="en">Double G clef. Sounds one octave lower than G clef. (See remarks on usage below.)</desc>
</valItem>
<valItem ident="F">
<desc xml:lang="en">F clef (Unicode 1D122).</desc>
</valItem>
<valItem ident="C">
<desc xml:lang="en">C clef (Unicode 1D121).</desc>
</valItem>
<valItem ident="perc">
<desc xml:lang="en">Drum clef (Unicode 1D125 or Unicode 1D126).</desc>
</valItem>
<valItem ident="TAB">
<desc xml:lang="en">Tablature "clef";
<abbr>i.e.</abbr>, usually "TAB" rendered vertically.</desc>
</valItem>
</valList>
</content>
<remarks xml:lang="en">
<p>Double-G clefs sound one octave lower, so do not combine with <att>dis</att>/
<att>dis.place</att>/<att>clef.dis</att>/<att>clef.dis.place</att>. In some cases
the double G clef may be used to indicate that two voices share one staff and
does not sound one octave lower. In this case the <att>oct</att> attribute may be
used to clarify the sounding octave of the instruments for the clef.
</p>
</remarks>
</macroSpec>