function ellipsis(x, maxlen)
{
/* given a string and a maximum length for the string, this routine
returns the same string truncated to the maximum length. In addition,
if the string was truncated, "..." is added to the end, again not to
exceed the maximum length.

E.g. ellipsis("abcdef", 4) = "a..."
ellipsis("abcdef", 6) = "abcdef"
*/

if (x.length <= maxlen)
return x
else if (maxlen < 4)
return x.substring(0, maxlen) // no room for ellipsis
else return x.substring(0, maxlen-3) + "...";
}