function parse_extra_field(blob/*:CFBlob*/)/*:any*/ {
	prep_blob(blob, 0);
	var o = /*::(*/{}/*:: :any)*/;
	var flags = 0;
	while(blob.l <= blob.length - 4) {
		var type = blob.read_shift(2);
		var sz = blob.read_shift(2), tgt = blob.l + sz;
		var p = {};
		switch(type) {
			/* UNIX-style Timestamps */
			case 0x5455: {
				flags = blob.read_shift(1);
				if(flags & 1) p.mtime = blob.read_shift(4);
				/* for some reason, CD flag corresponds to LFH */
				if(sz > 5) {
					if(flags & 2) p.atime = blob.read_shift(4);
					if(flags & 4) p.ctime = blob.read_shift(4);
				}
				if(p.mtime) p.mt = new Date(p.mtime*1000);
			}
			break;
		}
		blob.l = tgt;
		o[type] = p;
	}
	return o;
}