[RedCrowbar]

The [bracketed expression] is a target object type specifier in a path expression and can appear at any point in the path:

  User.<assignee[IS PullRequest].assignees[IS User].name

The reason for the FILTER clause is that you may want to write something like:

  FILTER User.name = 'Alice' OR User.<assignee[IS PullRequest].status = 'Open'

which is impossible to express if we were to simply filter each node set in the path separately.