K2-Steps-21 fails static type checking.  Since function argument $arg is has implicit type item()*, $arg/@e may fail with XPTY0019 (the result of a step in path expression must not be an atomic value).

(:*******************************************************:)
(: Test: K2-Steps-21                                     :)
(: Written by: Frans Englich                             :)
(: Date: 2007-11-22T11:31:21+01:00                       :)
(: Purpose: Tricky combination of focuses and function calls. :)
(:*******************************************************:)
declare variable $root :=
<a>
    <b e="B"/>
    <c e="B"/>
</a>;
declare function local:function($arg)
{
$root["B" eq $arg/@e]
};
$root/local:function(c)