Data extraction from string or wireframe contours

There are several ways to extract a subset from a larger dataset in MM 2016, but I can't give you a definite answerwithout knowing exactly what kind of data you are using and what kind of result you want. Here are some suggestions:

For strings (e.g. contour lines) you can use the interactive Clip Strings button on the String Tools toolbar to clip the strings using another string file or a wireframe.

If you want to incorporate this in a macro, select Strings | Clip on the main menu and then use the To Polygon or To Wireframe option.

For wireframes, use the interactive Cut Wireframe button on the Wireframe Tools toolbar, or Wireframe | Operations | Cut on the main menu.

If you just want to select data points falling within a polygon, use one of the Mark points as selected options on the Select toolbar.