-@code{instrumentName} clearly lives in the @code{Staff} context, since
-it is the staff that is to be named.
-In this example the first staff is labeled, but not the second,
-because we omitted the context name.
+@code{clefGlyph} clearly lives in the @code{Staff} context, since
+it is the staff's clef glyph that is to be changed.
+In this example the first staff's clef is printed correctly, but not the
+second -- which prints the default treble clef instead of the
+expected bass (or F) clef -- because we omitted the context name.