NavigationInfo{ type "EXAMINE" }
  Viewpoint{ fieldOfView .2 position 0 0 40 description "[100]"}
  Viewpoint{ fieldOfView .2 position 28 0 28 orientation 0 1 0 .785 description "[110]"}
  Viewpoint{ fieldOfView .2 position 23 23 23 orientation -1 1 0 .955 description "[111]"}
  DEF XForm Transform{ children[] }
  Script{
    field SFNode XForm USE XForm
    directOutput TRUE
  url ["javascript:
  function initialize() { 
    var i,j,k, n=2, is=1,js,ks, Str = '';
    for ( i= -n; i<= n; i++) {
      js = is; sj='';
      for ( j= -n; j<= n; j++) {
        ks = js;  sk = '';
        for ( k= -n; k<= n; k++) {
          if (ks < 0) sk += 'Na{ trans '+i+' '+j+' '+k+'}';
          else sk += 'Cl{ trans '+i+' '+j+' '+k+'}';
          ks = -ks;}
        sj += sk; js = -js;}
      Str += sj; is = -is;}
    XForm.addChildren = Browser.createVrmlFromString(
  'PROTO Grid[]{'+
  'Shape{ appearance Appearance{ material Material{ emissiveColor 1 1 1}}'+
  'geometry IndexedLineSet{ coord Coordinate{'+
  'point[.5 0 0, -.5 0 0, 0 .5 0, 0 -.5 0, 0 0 .5, 0 0 -.5]}'+
  'coordIndex[0 1 -1 2 3 -1 4 5]}}}'+
  'PROTO Na[ field SFVec3f trans 0 0 0]{'+
  'Transform{ translation IS trans children[ Grid{}'+
  'Shape{ appearance Appearance{ material Material{ diffuseColor .9 .9 1 } }'+
  'geometry Sphere{ radius 0.15 }}]}}'+
  'PROTO Cl[ field SFVec3f trans 0 0 0]{'+
  'Transform{ translation IS trans children[ Grid{}'+
  'Shape{ appearance Appearance{ material Material{ diffuseColor 1 1 0 } }'+
  'geometry Sphere{ radius 0.2 }}]}}' + Str );
  }"]
  }