tie break on multiple parents
@@ -148,8 +148,11 @@ relationship can be expressed in one of two ways:
`canonical` determines whether this is the main parent for the space. When
a user joins a room with a canonical parent, clients may switch to view
- the room in the context of that parent space, peeking into it in order to
- find other rooms and group them together.
+ the room in the context of that space, peeking into it in order to find
+ other rooms and group them together. In practice, well behaved rooms
+ should only have one `canonical` parent, but given this is not enforced:
+ if multiple are present the client should select the one with the lowest
+ room ID, as determined via a lexicographic utf-8 ordering.
To avoid abuse where a room admin falsely claims that a room is part of a
space that it should not be, clients could ignore such `m.space.parent`
