What are the goal-circle rules for goalkeepers and defenders?

Under Rule 17 of the World Lacrosse Women's Field Rules:

• A goalkeeper or defender has possession in the goal-circle if they have one or both feet grounded in it and the ball is in their crosse (or is in the circle and in the pocket or trapped under the goalkeeper's crosse). A defender cannot cover the ball; only the goalkeeper can trap it.
• The goalkeeper's crosse cannot be checked while they have possession in the circle. A defender's crosse can be checked.
• They must move the ball out of the circle within 5 seconds of gaining possession.
• Once the ball has been moved out, the defending team must not return it to the goal-circle until it has been played. A goalkeeper or defender cannot re-enter the circle with the ball in their crosse.
• The Lacrosse Canada summary adds that defenders may move through the circle at any time but may not remain in it, and that a goalkeeper with one foot in and one foot out is in the circle.