<entry term="crystal system" id="cryst1" dataType="string">
  <definition>A crystal system</definition>
  <enumeration value="triclinic">
    <annotation>
      <documentation>
        <div class="summary">No constraints on lengths and angles</div>
      </documentation>
    </annotation>
  </enumeration>
  <enumeration value="monoclinic">
    <annotation>
      <documentation>
        <div class="summary">Two cell angles are right angles; no other constraints</div>
      </documentation>
    </annotation>
  </enumeration>
  <enumeration value="orthorhombic">
    <annotation>
      <documentation>
        <div class="summary">All three angles are right angles; no other constraints</div>
      </documentation>
    </annotation>
  </enumeration>
  <enumeration value="tetragonal">
    <annotation>
      <documentation>
        <div class="summary">Fourfold axis of symmetry; All three angles are right angles; two equal cell lengths; no other constraints</div>
      </documentation>
    </annotation>
  </enumeration>
  <enumeration value="trigonal">
    <annotation>
      <documentation>
        <div class="summary">Threefold axis of symmetry; Two angles are right angles; one is 120 degrees; two equal lengths; no other constraints</div>
      </documentation>
    </annotation>
  </enumeration>
  <enumeration value="hexagonal">
    <annotation>
      <documentation>
        <div class="summary">Sixfold axis of symmetry; Two angles are right angles; one is 120 degrees; two equal lengths; no other constraints</div>
      </documentation>
    </annotation>
  </enumeration>
  <enumeration value="cubic">
    <annotation>
      <documentation>
        <div class="summary">All three angles are right angles; all cell lengths are equal</div>
      </documentation>
    </annotation>
  </enumeration>
</entry>