loat(a[0].replace(/[^0-9.-]/g,''));
    if (isNaN(aa)) aa = 0;
    bb = parseFloat(b[0].replace(/[^0-9.-]/g,'')); 
    if (isNaN(bb)) bb = 0;
    return aa-bb;
  },
  sort_alpha: function(a,b) {
    if (a[0]==b[0]) return 0;
    if (a[0]<b[0]) return -1;
    return 1;
  },
  sort_ddmm: function(a,b) {
    mtch = a[0].match(sorttable.DATE_RE);
    y = mtch[3]; m = mtch[2]; d = mtch[1];
    if (m.length == 1) m = '0'+m;
    if (d.length == 1) d = '0'+d;
    dt1 = y+m+d;
    mtch = b[0].match(sorttable.DATE_RE