This is an archived snapshot of W3C's public bugzilla bug tracker, decommissioned in April 2019. Please see the home page for more details.
In 3.11.2.2 Array Lookup using Function Call Syntax we read: "If position n does not exist in the array, a dynamic error is raised [err:FOAY0001] ." Here the error code [err:FOAY0001] is not linked to its definition.
I note that errors defined in F&O in general aren't linked. So I presume this is intentional.