Once a private character has been declared using a <glyph-data> element, the character need not be defined with the same <glyph-data> element every time it is used. The character can be reused by using the <glyph-ref> element to point to the full <glyph-data> element. The pointing uses the ID/IDREF mechanism, using the @glyph-data attribute of the <glyph-ref> element to point to the @id attribute of an existing <glyph-data> element. Since the reference uses the ID/IDREF, the reference may precede or follow the element to which it is pointing.
<!ELEMENT glyph-ref EMPTY >
This is an EMPTY element
...
<p>...The map symbol indicating these conditions will be a
<private-char name="NORTHWEST SOUTHEAST ARROW" description="Arrow,
normal weight, single line, two-headed, Northwest to Southeast">
<glyph-data id="NWSEArr" format="PBM" resolution="300"
x-size="34" y-size="34">
0000000000000000000000000000000000 0111111111111100000000000000000000
0111111111111100000000000000000000 0111110000000000000000000000000000
0111110000000000000000000000000000 0111111000000000000000000000000000
0110111100000000000000000000000000 0110011110000000000000000000000000
0110001111000000000000000000000000 0110000111100000000000000000000000
0110000011110000000000000000000000 0110000001111000000000000000000000
0110000000111100000000000000000000 0110000000011110000000000000000000
0110000000001111000000000000000000 0110000000000111100000000000000000
0110000000000011110000000000000000 0000000000000001111000000000000000
0000000000000000111100000000000110 0000000000000000011110000000000110
0000000000000000001111000000000110 0000000000000000000111100000000110
0000000000000000000011110000000110 0000000000000000000001111000000110
0000000000000000000000111100000110 0000000000000000000000011110000110
0000000000000000000000001111000110 0000000000000000000000000111100110
0000000000000000000000000011110110 0000000000000000000000000001111110
0000000000000000000000000001111110 0000000000000000011111111111111110
0000000000000000011111111111111110 0000000000000000000000000000000000
</glyph-data></private-char>. The NOAA 1993 standard definition of
<private-char name="NORTHWEST SOUTHEAST ARROW" description="Arrow,
normal weight, single line, two-headed, Northwest to Southeast">
<glyph-ref glyph-data="NWSEArr"/></private-char> will apply.
</p>
...
JATS-chars1.ent