For example in the filter expression $x[count(.|$y)=count($y)] (which is the only convenient way in XSLT 1.0 of doing a setintersection operation), Saxon will evaluate count($y) only once.
The permissions sets of the caller class and its ancestors (that is, all stack frames above this one) are not included in computing the intersectionset.
调用类和它的上级(即所有在它 上面的堆栈帧)的权限集都 不包括在交集计算中。
3
The resulting set will be the intersection of the resulting sets of each spec.