function calc_legend($grenzen_zas)
{
global $legend, $zmax, $zgrenzen;
// calculate the legend values
$hulpar = explode(',', $grenzen_zas);
$i = 1;
// I18N: %d is a year
$date = new WT_Date('BEF ' . $hulpar[0]);
$legend[0] = strip_tags($date->display());
$zgrenzen[0] = $hulpar[0] - 1;
while (isset($hulpar[$i])) {
$i1 = $i - 1;
$date = new WT_Date('BET ' . $hulpar[$i1] . ' AND ' . ($hulpar[$i] - 1));
$legend[$i] = strip_tags($date->display());
$zgrenzen[$i] = $hulpar[$i] - 1;
$i++;
}
$zmax = $i;
$zmax1 = $zmax - 1;
// I18N: %d is a year
$date = new WT_Date('AFT ' . $hulpar[$zmax1]);
$legend[$zmax] = strip_tags($date->display());
$zgrenzen[$zmax] = 10000;
$zmax = $zmax + 1;
if ($zmax > 8) {
$zmax = 8;
}
}