Attributes

An attribute is a relation elevated with type and cardinality constraints. Where a raw claim like com.app.person/name just associates a value with an entity, an attribute says: “this relation accepts Text values and each entity has exactly one.”

Attributes are the building blocks of concepts.

Defining Attributes

Via the CLI

carry assert attribute @person-name \
  the=com.app.person/name \
  as=Text \
  cardinality=one \
  description="Name of a person"

The @person-name creates a bookmark so you can reference this attribute by name later.

Via YAML

person-name:
  attribute:
    description: Name of a person
    the: com.app.person/name
    as: Text
    cardinality: one

The top-level key (person-name) becomes the bookmark name.

Attribute Fields

Field	Required	Description
`the`	Yes	The relation identifier – `domain/name` format
`as`	Yes	The value type (see below)
`cardinality`	No	`one` (default) or `many`
`description`	Yes	Human-readable description

Value Types

Type	Description	Example Values
`Text`	UTF-8 string	`"Alice"`, `"hello world"`
`UnsignedInteger`	Non-negative integer	`0`, `28`, `1000`
`SignedInteger`	Signed integer	`-5`, `0`, `42`
`Float`	Floating-point number	`3.14`, `-0.5`
`Boolean`	True or false	`true`, `false`
`Symbol`	A namespaced constant	`carry.profile/work`
`Entity`	Reference to another entity	`did:key:z...`
`Bytes`	Raw binary data	(binary)

You can also specify an enumeration of allowed symbols:

task-status:
  attribute:
    description: Current status of a task
    the: com.app.task/status
    as: [":todo", ":in-progress", ":done"]
    cardinality: one

Cardinality

one – Each entity has at most one value for this attribute. Asserting a new value replaces the old one.
many – Each entity can have multiple values. Asserting adds to the set; retracting a specific value removes it.

# A person has one name
person-name:
  attribute:
    description: Name
    the: com.app.person/name
    as: Text
    cardinality: one

# A recipe can have many ingredients
recipe-ingredient:
  attribute:
    description: An ingredient in the recipe
    the: diy.cook/ingredient
    as: Entity
    cardinality: many

Attribute Identity

Two attributes with the same relation identifier (the) but different type or cardinality are distinct entities. The attribute’s DID is derived from the hash of (relation_id, type, cardinality). The description does not affect identity.

This means you can have, for example, both a Text version and an Entity version of the same relation, and they will be treated as different attributes.

Querying Attributes

# List all defined attributes
carry query attribute

# Find a specific attribute by name
carry query attribute the=com.app.person/name

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