When you join another players game and you see N/A in all the settings for world shape and continent shape, what does that mean, and how do you get that setting?

Not available - when some1 dont choose option for map.

How do you not select a map?

Does this mean that the map played on was built by someone, and not randomly generated?

Was this map randomly generated but played on before?

If so would this be fair to those who have never played on this map, and can someone force the map engine so they start in a specific place on the map?