1<doc>
2  <!-- at least one present -->
3  <z-o>
4    <b/>
5  </z-o>
6  <o-o>
7    <c/>
8  </o-o>
9  <z-u>
10    <d/>
11  </z-u>
12  <o-u>
13    <e/>
14  </o-u>
15  <z-3>
16    <f/>
17  </z-3>
18  <o-3>
19    <g/>
20  </o-3>
21  <!-- more than one present when allowed -->
22  <z-o>
23    <b/>
24  </z-o>
25  <o-o>
26    <c/>
27  </o-o>
28  <z-u>
29    <d/>
30    <d/>
31    <d/>
32  </z-u>
33  <o-u>
34    <e/>
35    <e/>
36    <e/>
37  </o-u>
38  <z-3>
39    <f/>
40    <f/>
41    <f/>
42  </z-3>
43  <o-3>
44    <g/>
45    <g/>
46    <g/>
47  </o-3>
48  <!-- min 0 are not present -->
49  <z-o/>
50  <o-o>
51    <c/>
52  </o-o>
53  <z-u/>
54  <o-u>
55    <e/>
56  </o-u>
57  <z-3/>
58  <o-3>
59    <g/>
60  </o-3>
61</doc>
62