function fillCategory(){
addOption(document.drop_list.Category, "Algemeen", "Algemeen", "");
addOption(document.drop_list.Category, "Ruimtevaart", "Ruimtevaart", "");
addOption(document.drop_list.Category, "Sterrenkunde", "Sterrenkunde", "");
addOption(document.drop_list.Category, "Wetenschap", "Wetenschap", "");
}
function SelectSubCat(){
removeAllOptions(document.drop_list.SubCat);
if(document.drop_list.Category.value == 'Algemeen'){
addOption(document.drop_list.SubCat,"0", "Verenigingen");
addOption(document.drop_list.SubCat,"1", "Partners");
}
if(document.drop_list.Category.value == 'Ruimtevaart'){
addOption(document.drop_list.SubCat,"2", "Organisaties");
addOption(document.drop_list.SubCat,"3", "Educatief");
addOption(document.drop_list.SubCat,"4", "Kids");
addOption(document.drop_list.SubCat,"5", "Actualiteit");
addOption(document.drop_list.SubCat,"6", "Varia");
}
if(document.drop_list.Category.value == 'Sterrenkunde'){
addOption(document.drop_list.SubCat,"7", "Organisaties");
addOption(document.drop_list.SubCat,"8", "Educatief");
addOption(document.drop_list.SubCat,"9", "Kids");
addOption(document.drop_list.SubCat,"10", "Actualiteit");
addOption(document.drop_list.SubCat,"11", "Varia");
}
if(document.drop_list.Category.value == 'Wetenschap'){
addOption(document.drop_list.SubCat,"12", "Organisaties");
addOption(document.drop_list.SubCat,"13", "Weerkunde");
addOption(document.drop_list.SubCat,"14", "Andere Wetenschappen");
}
if(document.drop_list.Category.value == 'categorie'){
addOption(document.drop_list.SubCat,"", "Onderwerpen"); }
}
function removeAllOptions(selectbox)
{
	var i;
	for(i=selectbox.options.length-1;i>=0;i--)
	{
		selectbox.remove(i);
	}
}


function addOption(selectbox, value, text )
{
	var optn = document.createElement("OPTION");
	optn.text = text;
	optn.value = value;

	selectbox.options.add(optn);
}