// Function which swaps display between tabs
      var sectionName = "A7";
      
      function changeTab (tabID) {
      if (isvalidTab(tabID))
      {
          // toggle the tab divs on/off
          document.getElementById('tab_overview').style.display = 'none';
          document.getElementById('tab_documentation').style.display = 'none';
          document.getElementById('tab_training').style.display = 'none';
          document.getElementById('tab_samples').style.display = 'none';
          document.getElementById('tab_conversations').style.display = 'none';
          document.getElementById('tab_'+tabID).style.display = 'block';

          // toggle the tab image
          if (document.getElementById('tabnav_overview') != undefined)
          { document.getElementById('tabnav_overview').className = 'btab'; }
          if (document.getElementById('tabnav_documentation') != undefined)
          { document.getElementById('tabnav_documentation').className = 'btab'; }
          if (document.getElementById('tabnav_training') != undefined)
          { document.getElementById('tabnav_training').className = 'btab'; }
          if (document.getElementById('tabnav_samples') != undefined)
          { document.getElementById('tabnav_samples').className = 'btab'; }
          if (document.getElementById('tabnav_conversations') != undefined)
          { document.getElementById('tabnav_conversations').className = 'btab'; }

          document.getElementById('tabnav_' + tabID).className = 'wtab';
        }
      }
      
      function isvalidTab (tabID) {
        if (tabID == 'overview' || tabID == 'documentation' || tabID == 'training' || tabID == 'samples' 
            || tabID == 'conversations'  )  {
            return true; }
          else { return false; }
      }

      /* ************************************************************
      /* Expand / Collapsing  entries
      /* toggle expands collapsed  sections and collapses expanded
      /* sections when called.  Called by clicking on the + or - icon at
      /* the left of an entry. 
      /* Parameters:
      /* element:  the <img> html tag of the clickable icon
      /* blockid:  the id value of the <div> tag containing the 
      /*           section to be toggled.
      /* ***********************************************************  */
      function toggle(element, blockid) {
          //alert(element.src);
          //alert(element.className);
          //alert(blockid);

          if (element.className == 'collapse') {
              // Collapse the block and reset toggle to expand
              element.className = 'expand'
              element.src = '/images/product/plus.png'
              document.getElementById(blockid).style.display = 'none';
          }
          else {
              // Expand the block and reset toggle to collapse
              element.className = 'collapse'
              element.src = '/images/product/minus.png'
              document.getElementById(blockid).style.display = 'block';
          }

      }