Originally Posted by Efrem

A surface sector, as you probably know, is a part of your trip that is on land or water rather than in the air. As I understand it, the other terms mean:

An embedded surface sector is between two points in the same direction. For example, say you want to go from Chicago to Paris, with a change in New York. Your Chicago flight is ORD-LGA. Your Paris flight is JFK-CDG. LGA-JFK is an embedded surface sector. That is permitted under this fare rule.

A fare break surface sector is a surface sector at one end of your air travel or the other. (Those are fare break points, also called fare construction points.) Say you wanted to continue from CDG to Nice via the TGV, ending your journey there. That would not be permitted under this fare rule. It basically means "no surface travel before your first flight or after your last one," applied separately to each part of your total journey (e.g., outbound and return).