function increasefield(strfieldid){var obj=document.getElementById(strfieldid);var value=parseInt(obj.value);if( isNaN(value))value=0;obj.value=value+1;}
function decreasefield(strfieldid){var obj=document.getElementById(strfieldid);var value=parseInt(obj.value);if( isNaN(value) ) value=0;obj.value=--value>=0?value:0;}