If <group-name-display> is
given, it overrides <group-name> for display.
The first two staves use only <group-name>, while the third and
fourth one (with the same <group-name> value) override it with
a custom text.
In a similar vein, <group-abbreviation> can be overridden with
<group-abbreviation-display>, shown in the second system.
The multi-line entries are generated by using ‘xml:space="preserve"’
as an attribute within a <display-text> child of the
<xxx-display> element.
Group Name
G. N.
bracket
no
Group Name
Group Name
Override
G. N.
G. N.
Overr.
bracket
no
1
C
4
4
1
whole
C
4
4
1
whole
1
C
4
4
1
whole
C
4
4
1
whole
1
C
4
4
1
whole
C
4
4
1
whole
1
C
4
4
1
whole
C
4
4
1
whole