i just did a quick search but all i found was on c++. i used it for a brief test before recommending it and its pretty straightforward basically you input a point and it tells you if theres navigation data where the point is. when i tested it i tried with inputting the nav data via a public variable and with leaving the nav data pin empty and both seemed to work. as for the query extent i havent really tried that out yet so i couldnt tell you. i was just using the node to ensure that the point your looking to move to is some where the character can navigate to.