# 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 Abstract Class: QTY
This class is the abstract generalization of all classes whose instances are used to model quantities. All quantities are numeric such that (a) the order of the numbers reflects an order relation (less-or-equal) defined for the quantified attribute and (b) the differences between the numbers reflect differences of the attribute. ## Specializes ## ANY ## Attributes
Name | Data type | Occurs | Description
--- | --- | --- | ---
expression | ED | 0..1 | in ISO 21090 the expression attribute allows for a specification of a derived value given contextual information, using an expression language such as OCL. It is intended in the LRA to make such derived values explicitly stated in terms of queries against a logical model. Use of this attribute is deprecated in the LRA.
expressionLanguage | Code | 0..1 | This is implemented as described in ISO 21090.
originalText | ED.Text | 0..1 | In the context of the LRA, in which a system is populating a QTY data value based on a locally held value, it is possible that the original text will not be known. This is an optional value in ISO 21090 and must not be relied upon to be populated in the LRA. In implementation there is expected to be specific rendering rules associated with individual user interface designs, for a given data point. It is a conforming systems responsibility to ensure that the actual value is semantically equivalent to the user input value.
uncertainty | QTY | 0..1 | Expression of uncertainty expressed by this attribute is to some extent replicated by other datatypes in the specification (specifically URG). This uncertainty attribute describes uncertainty arising as a result of knowable limits to the precision of a measuring instrument - where there is, for example, a measured value and an expression of confidence that the value is correct. It is different from precision of the numeric representation in terms of significant digits. This is differentiated in ISO 21090 from an expression of uncertainty in the actual value of a measured attribute, which is represented as an uncertain range. In the LRA it is not felt that the expression of that confidence is significantly different. When required in medicine it is frequently expressed the same way, with expression of simple 95% (possibly assymetric) confidence limits. This expression does not directly support such examples (e.g. relative risk = 0.2 wth 95% confidence interval 0.01 - 0.21), is felt to potentially confuse, be unsupported by the majority of current clinical applications, and as such this attribute is deprecated from the LRA for the time being.
uncertaintyType | UncertaintyType | 0..1 | As above this is deprecated in the LRA.
## Constraints
Type | Name | Specification
--- | --- | ---
no datatype uncertainty in LRA | LRA Invariant | inv: uncertainty.oclIsUndefined and uncertaintyType.oclIsUndefined
no expression calculation in LRA | Invariant | inv: expression.oclIsUndefined and expressionLanguage.oclIsUndefined
No History or Update Mode | Invariant | inv: noUpdateOrHistory(uncertainty) and noUpdateOrHistory(originalText) and noUpdateOrHistory(expression)
uncertainty | Invariant | inv: uncertainty.isNotNull implies (uncertainty.expression.isNull and uncertainty.uncertainty.isNull and uncertainty.originalText.isNull) --- nullFlavor related