function	klickezurechner(x)
		{	
			document.getElementById("txt_kwhindex").value=(x);						
			schreibeWerte();
			return true;			
		}

function schreibeWerte()
 		{ 			
 			var kwhtemp = 0;
 			var plztemp = 0;
 			var abschlag = 0;
 			
 			a = document.forms['kurzrechner'];		 
			kwhtemp = a.txt_kwhindex.value; 
			plztemp = a.txt_plzindex.value; 		   
			reg5num = new RegExp ('^[0-9]{5}$');
			reg4num = new RegExp ('^[0-9]{4,5}$');
 		   
 		   document.getElementById("plzdisplay").innerHTML=(plztemp.valueOf());
			document.getElementById("kwhdisplay").innerHTML=(kwhtemp.valueOf());			 	

			if(reg4num.test(a.txt_kwhindex.value) == false)
				{	
			 		document.getElementById("kwhdisplay").style.color="red";
			 		kwhvalide = false;
				}
			else
				{
					document.getElementById("kwhdisplay").style.color="black";
					kwhvalide = true;
						
						if(a.txt_kwhindex.value >= 17000)
							{	
			 					document.getElementById("kwhdisplay").style.color="red";
			 					kwhvalide = false;
							}			
				}
			if(reg5num.test(a.txt_plzindex.value) == false)
				{	                   				           
			 		document.getElementById("plzdisplay").style.color="red";
			 		plzvalide = false;
				}
			else
				{ 
					document.getElementById("plzdisplay").style.color="black";
					plzvalide = true;					
				}		
			
			if ( kwhvalide && plzvalide == true)
				{
					a.angebotberechnen.disabled= false;							
					abschlag = (kwhtemp*arbeitspreis/12)+grundgebuehr;	   			
					return true;
				}								   
			else
				{
					return false;
				}								 			   
 		}