Protect Specific Characters from Interpretation
Theoretically, it is possible that your documents URIs contain some characters that may enter in conflict with the characters used in the grammar described. In such case, to avoid a parsing exception, you can protect these special characters using the simple quote character to protect your graph matching expression.
So the expression: -node['xd/df-ty/x.b*'].'a|b'
is equivalent to the
expression: -node[X].Y