On the command line, it is now possible to set the value of an external variable to a zero-length
string by writing
Saxon now checks for the new error XQST0093 which was introduced in the Proposed Recommendation. This error
makes it illegal for a function or variable in module A to reference a function or variable in module B if there
is a function or variable in module B that references one in A. Because this restriction is quite unnecessary
and makes it very difficult to write modular applications, there is a new option
declare option saxon:allow-cycles "true" to disable this check. This new option also disables
error XQST0073, which otherwise occurs when two modules in different namespace import each other.