# 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: PQ
in ISO 21090 this represents an real value associated with a UCUM unit as a text string. ## Specializes ## PQV ## Attributes
Name | Data type | Occurs | Description
--- | --- | --- | ---
translation | PQR | 1..1 | in ISO 21090 the translation attribute specifies a set of equivalent measurements in to non UCUM units (but not between UCUM units). This "translation" is in fact a prospective transformation. It is possible, as with the generalisation PQV to maintain a longitudinal record of performed transformations using the source attribute. A prospective translation in PQ has a single known use case, which is the dual expression of a drug dose in UCUM and DM&D units, which is described in the MiM HL7 data types implementation. For that purpose it is retained. It should not be used for any other purpose unless a clear implementation guide can be produced. This is implemented as described in ISO 21090.
unit | UcumUnitOfMeasure | 0..1 | Attribute constrained for use within the LRA to UcumUnitOfMeasure.
## Constraints
Type | Name | Specification
--- | --- | ---
code is type UcumUnitOfMeasure | LRA Invariant | inv: code.oclIsKinfOf(UcumUnitOfMeasure)
no translation if null | Invariant | inv: isNull implies translation->isEmpty --context PQ::isDifference(other : QTY): Boolean -- post: other.oclIsKindOf(PQ) and canonical.units.equals(other.oclAsTypeOf(PQ).canonical.units)
null or value | Invariant | inv: isNull xor value.oclIsDefined -- nullFlavor invariants