Stores true/false values. Note that, as a general rule, you can Console or the Configuration APIs to set a boolean value to null instead of true or false. A null value effectively indicates that the user has not entered a value for the attribute in question; for example, a user hasn't accept a user consent (true) nor has the user declined the consent (false).
When creating a boolean attribute the following validations and transformations are available to you:
Globally unique attributes must be unique among all the entities in the entity type. Locally unique attributes must be unique across all the plural attributes in a single entity (e.g., a single user profile).
The attribute must contain a non-null value.
Makes the attribute a primary key for the plural or entity type it exists in; this enables you to use API calls to target a specific record in a plural without knowing the actual identifier for that record. To set a primary key you also need the required constraint and either a unique or a locally-unique constraint.
Attributes that can be written to one time, then are never changed.