Uhr1_Row1=this.getField("Uhr1_Row1").value;  
Uhr2_Row1=this.getField("Uhr2_Row1").value;  
 
var StartZeit = Uhr1_Row1.substr(0,2) * 60 + Uhr1_Row1.substr(3,2) * 1;  
var EndeZeit = Uhr2_Row1.substr(0,2) * 60 + Uhr2_Row1.substr(3,2) * 1;  
var DiffZeit = ((EndeZeit + 24*60) - StartZeit) % (24*60);  
var DauerH = Math.floor(DiffZeit/60);  
var DauerM = DiffZeit - (DauerH * 60);  
 
if (DauerH == 0) {  
event.value = ''  
} else {  
event.value = DauerH+DauerM/60  
} 

  
if ((this.getField("Std_Row1").value==0) && (this.getField("Std_Row2").value==0) && (this.getField("Std_Row3").value==0) && (this.getField("Std_Row4").value==0))  
{  
this.getField("Gesamt_Std").value='';  
}  
else  
{  
this.getField("Gesamt_Std").value=((this.getField("Std_Row1").value)+(this.getField("Std_Row2").value)+(this.getField("Std_Row3").value)+(this.getField("Std_Row4").value));  
}