A transport is an object that helps the player move. It should not be confused an EXIT, which instantaneously transport a player from one map to another.
Instead, a transport may let the player move faster, give him move types they don't have, etc. A simple example of this would a horse. It doesn't let the player move anyplace he normally couldn't go, but lets him get there faster. Ships would be another case - the player normally can't move across water, but with a ship, he can.
animation full anim_full It may be desirable to have different animations to denote what the transport looks like if someone is on it vs. not (mounted horse vs. just a horse). This is used to denote what it will look like when loaded. If the transport becomes empty, it will fall back to the archetype animation.
base speed base_speed This is only needed if <weight speed ratio> is set - it is used to know what the base speed to use in the calculation (since speed is getting clobbered). If this is not set and <weight speed ratio> is set, the archetype's speed will be used.
face full face_full It may be desirable to have different faces to denote what the transport looks like if someone is on it vs. not (mounted horse vs. just a horse). This is used to denote what it will look like when loaded. If the transport becomes empty, it will fall back to the archetype face.
move allow obj::move_allow The move type the transport grants, regardless of other objects on this square.
move type obj::move_type The move type the transport uses.
movement speed obj::speed How fast the transport moves.
passenger limit passenger_limit How many players this transport can hold. Thus, boats can transport a party (this being set to 6) while horses could only transport a single person. If this is not set, a default of 1 will be used.
weight limit obj::container How much this transport can carry.
Thus, if <weight factor> is 0, this object will move the same speed no matter how loaded it is. If it is 100, then if the transport is fully loaded, it moves at a crawl. In a sense, this somewhat mimics the player movement speed. Large transports, like boats, should likely be largely unaffected by weight (maybe have this value at 10), where something like a horse would have a relatively high value.