The XL query syntax uses the square brackets ([ and ]) as symbol for sub trees in the path pattern. Thus, there is a conflict between the syntax for element access in an array, and sub-tree predicate.

For instance, with N a type of Node, ar an array, the query: N ar[5] N is syntactically interpreted as four node patterns: N, ar, N, and 5 bracketed to define a branch.

The solution is to use the quote operator.

N `ar[5]` N