function classChange(pElemRef, pClass) { // called by most mouseover/out handlers
				//alert("In classChange");// debug alert
				pElemRef.className=pClass;
			}		

			function selectLab(pSelRef){ // pSelRef = reference to the select element for choosing a Lab# 
				//called by the select element for choosing a Lab# in page Lab#.html
				//alert("In selectLab, pSelRef= "+ pSelRef);// debug alert
				mLabNum = pSelRef.options[pSelRef.selectedIndex].value; //  = 0, 01 ... 25 (where 0 = Go To)
				//alert("In selectLab, mLabNum= "+ mLabNum);// debug alert
				if (mLabNum > 0) { // if a Lab# was selected 
					mLab = "../Lab" + mLabNum + "/Lab" + mLabNum + ".html"; // create "../Lab#/Lab#.html"
					//alert("In selectLab, mLab= "+ mLab);// debug alert
					document.location.href = mLab;
				}				
			}

			function goWhere(pPg) { // called by clicking a small image in page Lab#.html
				// shows a large image page (Img#-#.html)
				//alert("In goWhere"); // debug alert
				imgWindowRef= window.open(pPg,"imgWindow","scrollbars=yes,width=700,height=650,resizable,menubar=0,left=100");
			}		

			function alertUser() { // called by the two menu link items on home page
				// alerts user they are leaving this web site & to use back button
					alert("NOTE:\n\nYou have selected a link to another web site.\n\nUse the browser BACK button to return to this page.\n\n\n");
			}		

			function menuClick(pWhere) {
				document.location.href = pWhere; // load chosen page
			}		
			
			function keyInfo() { // called by ClickHere "buttton" in Large image "slide-show"
				// open window describing keyboard shortcuts (keyInfo.html)
				keyInfoWindowRef= window.open("../keyInfo.html","keyWindow","scrollbars=0,width=400,height=400,menubar=0,left=200,top=150");
			}
			
			// declare global varibles for Img#-#.html pages
			var gLabelsRef; // ref to div that contains the labels gif image 
			var gCurrPgPrefix ; // prefix for identifying a large image page for a Lab# eg, Img#- (connotes Lab#-)
			var gMaxPgNum ; // the maximum number of images in a Lab slide show of large images
			var gCurrPgNum; // number of the current iolarge image page (appended to the prefix)
	
			function init(pPage, pMax) { //called by onload handler of Img#-#.html page to load global vars
				//alert("In initialize, pPage = " + pPage); // debug alert
				gCurrPgPrefix = pPage.substring(0,(pPage.indexOf('-') +1)); //indexOf('-')); // eg, Img1-
				//alert ("gCurrPgPrefix = " + gCurrPgPrefix); // debug alert
				gCurrPgNum = pPage.substring((pPage.indexOf('-') +1), pPage.length);
				//alert ("gCurrPgNum = " + gCurrPgNum); // debug alert
				gMaxPgNum = pMax;
				gLabelsRef = (document.getElementById) ? document.getElementById('imgLabelsDiv') : ((document.all) ? document.all('imgLabelsDiv') : null) ; 
			}		

			function toggleLabels()	{ // called by Labels "buttton" in Large image "slide-show" or by spacebar
			   	//alert("In toggleLabels"); // debug alert
				if (gLabelsRef) { //  global ref to div containing labels
					if (gLabelsRef.style.visibility == 'visible') gLabelsRef.style.visibility = 'hidden';
					else gLabelsRef.style.visibility = 'visible';
				}
			}
					
			function closeWin(){ // called by Close "buttton" in Large image "slide-show"
				// closes a large image page (Img#-#.html)
				this.window.close();
			}

			function XXXXnewPage(pPage) { // called by Next/Previous "butttons" in Large image "slide-show"
				//alert("In newPage"); // debug alert
				document.location.href = pPage; // load chosen page
			}		

			function newPageCompute (pDirection) { // called by keyboard arrows in Large image "slide-show"
				//alert("In newPageCompute"); // debug alert
				var mPage = "" ;
				var mPgNum = gCurrPgNum; // load global into local var
				if (pDirection == 'next') { //left arrow key down
					mPgNum ++ ; // increment current page number
					if (mPgNum > gMaxPgNum) mPgNum = 1; //loop forward to first image after last image
					mPage = gCurrPgPrefix + mPgNum + ".html" ; //  eg, Img1- + 1 + .html= Img1-1.html
				}
				if (pDirection == 'previous') { //left arrow key down
					mPgNum -- ; // decrement current page number
					if (mPgNum < 1) mPgNum = gMaxPgNum; //loop back to last image after first image
					mPage = gCurrPgPrefix + mPgNum + ".html" ; //  eg, Img1- + 1 + .html= Img1-1.html
				}
				//alert("In newPageCompute, mPage = " + mPage); // debug alert
				document.location.href = mPage; // load chosen page
			}		

			function processKey(pEvnt) { // called by body onkeydowm event handler to process key down
			   //alert("In processKey, pEvnt = " +pEvnt); // debug alert
				evntRef = (pEvnt) ? pEvnt : ((window.event) ? event : null); // get ref to event object
				if (evntRef) { // not null
					switch (evntRef.keyCode) {
						case 37:
							 // alert("In processKey, left: evntRef.keyCode = " + evntRef.keyCode); // debug alert
							 newPageCompute ('previous');
							 break;					
						case 39:
							 // alert("In processKey, right: evntRef.keyCode = " + evntRef.keyCode); // debug alert
							 newPageCompute ('next');
							 break;
						case 27:
							 // alert("In processKey, esc: evntRef.keyCode = " + evntRef.keyCode); // debug alert
							 closeWin();
							 break;
						case 32:
							 //alert("In processKey, spacebar: evntRef.keyCode = " + evntRef.keyCode); // debug alert
							 toggleLabels();
							 break;
						default:
							 //alert("In processKey, key???: evntRef.keyCode = " + evntRef.keyCode); // debug alert
							 break;
					}
				}
			}