var currentindex=16;
				
			function collapseCategories(block_id) {
				for (block_num=0; block_num<categories_array.length; block_num++) {
					cat_id=categories_array[block_num];
					if (cat_id!=block_id) {
						document.getElementById(cat_id).style.display = "none";
						imageOff(block_num);
						}
					}
				}
			
			function toggleCategoryDisplay(block_index) {
				currentindex=block_index;
				block_id='category'+block_index;
				collapseCategories(block_id);
				if ( document.getElementById(block_id).style.display == "none" ) {
					document.getElementById(block_id).style.display = "block";
				} else {
					//document.getElementById(block_id).style.display = "none";
					}
				}

			var categories_array=new Array();
				categories_array[0]='category0';
				categories_array[1]='category1';
				categories_array[2]='category2';
				categories_array[3]='category3';
				categories_array[4]='category4';
				categories_array[5]='category5';
				categories_array[6]='category6';
				categories_array[7]='category7';
				categories_array[8]='category8';
				categories_array[9]='category9';
				categories_array[10]='category10';
				categories_array[11]='category11';
				categories_array[12]='category12';
				categories_array[13]='category13';
				categories_array[14]='category14';
				categories_array[15]='category15';
				
			//image swapping
			if (document.images) {
				//"ON" array	
				var onImgArray=new Array()
				onImgArray[0]= new Image(93,13)
				onImgArray[1]= new Image(93,13)
				onImgArray[2]= new Image(138,13)
				onImgArray[3]= new Image(209,13)
				onImgArray[4]= new Image(100,13)
				onImgArray[5]= new Image(187,13)
				onImgArray[6]= new Image(114,13)
				onImgArray[7]= new Image(99,13)
				onImgArray[8]= new Image(153,13)
				onImgArray[9]= new Image(93,13)
				onImgArray[10]= new Image(83,13)
				onImgArray[11]= new Image(136,13)
				onImgArray[12]= new Image(162,13)
				onImgArray[13]= new Image(147,13)
				onImgArray[14]= new Image(250,13)
				onImgArray[15]= new Image(157,13)

				//set URL's for "ON"
				onImgArray[0].src = "_img/buttons/clients/accounting_o.gif"
				onImgArray[1].src = "_img/buttons/clients/advertising_o.gif"
				onImgArray[2].src = "_img/buttons/clients/banking_finance_o.gif"
				onImgArray[3].src = "_img/buttons/clients/construction_engineering_o.gif"
				onImgArray[4].src = "_img/buttons/clients/call_centres_o.gif"
				onImgArray[5].src = "_img/buttons/clients/computing_technology_o.gif"
				onImgArray[6].src = "_img/buttons/clients/entertainment_o.gif"
				onImgArray[7].src = "_img/buttons/clients/government_o.gif"
				onImgArray[8].src = "_img/buttons/clients/hospitality_travel_o.gif"
				onImgArray[9].src = "_img/buttons/clients/industrials_o.gif"
				onImgArray[10].src = "_img/buttons/clients/insurance_o.gif"
				onImgArray[11].src = "_img/buttons/clients/legal_actuaries_o.gif"
				onImgArray[12].src = "_img/buttons/clients/management_services_o.gif"
				onImgArray[13].src = "_img/buttons/clients/mining_resources_o.gif"
				onImgArray[14].src = "_img/buttons/clients/pharmaceutical_health_o.gif"
				onImgArray[15].src = "_img/buttons/clients/telecommunications_o.gif"
				
				//"OFF" array	
				var offImgArray=new Array()
				offImgArray[0]= new Image(93,13)
				offImgArray[1]= new Image(93,13)
				offImgArray[2]= new Image(138,13)
				offImgArray[3]= new Image(209,13)
				offImgArray[4]= new Image(100,13)
				offImgArray[5]= new Image(187,13)
				offImgArray[6]= new Image(114,13)
				offImgArray[7]= new Image(99,13)
				offImgArray[8]= new Image(153,13)
				offImgArray[9]= new Image(93,13)
				offImgArray[10]= new Image(83,13)
				offImgArray[11]= new Image(136,13)
				offImgArray[12]= new Image(162,13)
				offImgArray[13]= new Image(147,13)
				offImgArray[14]= new Image(250,13)
				offImgArray[15]= new Image(157,13)

				//set URL's for "OFF"
				offImgArray[0].src = "_img/buttons/clients/accounting.gif"
				offImgArray[1].src = "_img/buttons/clients/advertising.gif"
				offImgArray[2].src = "_img/buttons/clients/banking_finance.gif"
				offImgArray[3].src = "_img/buttons/clients/construction_engineering.gif"
				offImgArray[4].src = "_img/buttons/clients/call_centres.gif"
				offImgArray[5].src = "_img/buttons/clients/computing_technology.gif"
				offImgArray[6].src = "_img/buttons/clients/entertainment.gif"
				offImgArray[7].src = "_img/buttons/clients/government.gif"
				offImgArray[8].src = "_img/buttons/clients/hospitality_travel.gif"
				offImgArray[9].src = "_img/buttons/clients/industrials.gif"
				offImgArray[10].src = "_img/buttons/clients/insurance.gif"
				offImgArray[11].src = "_img/buttons/clients/legal_actuaries.gif"
				offImgArray[12].src = "_img/buttons/clients/management_services.gif"
				offImgArray[13].src = "_img/buttons/clients/mining_resources.gif"
				offImgArray[14].src = "_img/buttons/clients/pharmaceutical_health.gif"
				offImgArray[15].src = "_img/buttons/clients/telecommunications.gif"
			}
			
			//to swap "ON"
			function imageOn(i) {
				if(document.images){
					document.images["btn" + i].src = onImgArray[i].src
				}
			}
			
			//to swap "OFF"
			function imageOff(i) {
				if(document.images){
					if ( currentindex!=i) {
						document.images["btn" + i].src = offImgArray[i].src;
						}
				}
			}