Algebraic sum of the transverse intersection points

Question

On page 61 of An introduction to knot theory by Lickorish, second paragraph, the author used the term “algebraic sum of the transverse intersection points”. I’ve never seen this when I read about knot theory or algebraic topology generally. Can you tell me what it means?

Answer 1

Problem solved, it’s something like counting how many times (with sign according to the orientations) the curve pass through the surface