Relations

A relation defines possible interactions between different kinds of objects. objects supports all the interactions defined by their kinds by default, exceptly ristricted by specially.

A relation is also an object.

Relation Object

Metadata

The metadata of a realtion object contains essential information about its type and versioning.

Field	Description
traits	Flags, 0 for now (reserved for future use)
rev	Revision number, starting with 0, increased after
krev	Revision of the Kind of Set
srev	Revision of the Set of Set
kind	The id of the kind object of this relation object
set	The id of the set object of this relation object

Elements

Index	Element	Mutable	Description
0	data	Yes	Shared data for all objects minted from this set
1	code	Yes	Address of the relation contract
2	poss	No	Address of the relation contract
3	adjs[0]	Yes	Shared data for all objects minted from this set
4	adjs[1]	Yes	Shared data for all objects minted from this set

Possession

The possession element defines the processing of the ownership of the departure objects when they are connected or disconnected from destination objects.

Adjacency

Each adj_spec_n element is composed of two tuples: (dep_kind, min, max), (dep_kind, min, max).

• dep_kind: The kind ID of the departure object, a uint64 integer.
• min: The minimum number of objects that the destination object can accept, a uint32 integer.
• max: The maximum number of objects that the destination object can accept, a uint32 integer.

The last tuple (dep_kind, min, max) of the last adj_spec_n can be all zeros, indicating the end of the adjacency spec array.

Normal dep_kinds must be an integer in the range of [1, (2^ - 2)].

A wildcard dep_kind has a value of 2^{32} - 1, meaning any kind.

The (dep_kind, min, max) tuples must be in increasing order. If a wildcard adjacency spec exists, it must be the last valid one.

min and max can be any uint32 integer in the range [0, (2^ - 1)], as long as max >= min.

If max equals (2^ - 1), it means unlimited.

Omni Registry

Set objects support the following operations:

Operation	Description
register_relation	Registers a new set into the registry.
update_relation	Updates the mutable elements of an existing set.
upgrade_relation	Applies a new revision of kind or set to the set object.