The in-line ref and each in-line that falls on the in-line increment will be output to file. The same logic is used to define the cross-line output.
For example, In-line Ref = 10, In-line Increment = 10, X-line Ref = 10, and X-line Increment = 20. Yields: in-lines 10, 20, 30, etc. and cross-lines 10, 30, 50, etc.
What do you want to do?