var subList                 = new Object();
    subList['about']        = 1;
    subList['services']     = 1;
    subList['industries']   = 1;
    subList['publications'] = 1;

    subList['operations']   = 0;
    subList['turnarounds']  = 0;
    subList['capital']      = 0;
    subList['realestate']   = 0;

function showSub(subID) {

  var subObject = document.getElementById('sub-' + subID);

  if( subObject ) {

    subObject.style.display = 'block';

    for(var subName in subList) {
      if( subList[subName] == 1 ) {
        document.getElementById('nav-' + subName + '-hover').style.visibility = subID == subName ? 'visible' : 'hidden';
      } else if ( subList[subName] == 0 && subID == subName ) {
        if( document.getElementById('nav-sub-' + subName + '-link') ) {
          document.getElementById('nav-sub-' + subName + '-link').className = 'nav-sub-arrow hovered';
        }
      }
    }

  }

} // ! showSub()

function hideSub(subID) {

  var subObject = document.getElementById('sub-' + subID);

  if( subObject ) {

    subObject.style.display = 'none';

    if( document.getElementById('nav-' + subID + '-hover') ) {

      document.getElementById('nav-' + subID + '-hover').style.visibility = 'hidden';

      for(var subName in subList) {
        if( subList[subName] == 0 ) {
          if( document.getElementById('nav-sub-' + subName + '-link') ) {
            document.getElementById('nav-sub-' + subName + '-link').className = '';
          }
        }
      }

    }

  }

} // ! hideSub()