# Logical Record Architecture for Health and Social Care
## Discharge Summary Release 0.02

Contents
The content of this release is not comprehensive and is not fully validated and must not be used in live system implementations.
# Reference Model Class: BL.Null
A LRA-specific flavor of the ISO 21090 BL data type which can only have a null flavor. ## Specializes ## BL ## Attributes
Name | Data type | Occurs | Description
--- | --- | --- | ---
value | Boolean | 0..1 | This is implemented as described in ISO 21090.
## Constraints
Type | Name | Specification
--- | --- | ---
is null | LRA Invariant | inv: not isNull.oclIsUndefined and value.oclIsUndefined
## Reference Model Type ##