Transformation Level 1

Terminology servers at Level 1 will accept any expressions represented in valid classifiable form, as in Level 0. Additionally, some expressions that are not already in classifiable form will also be accepted. These will mainly be syntactically compliant expressions that are not MRCM compliant, but which the server can unambiguously transform to derived expressions that are MRCM compliant, using predefined automated transforms.

Loose Attributes

A loose attribute is any attribute within a CTU expression that is not in an attribute group AND the MRCM specifies:

• that it should be grouped, or

• that it is in the wrong domain

Scope of Transformations

Level 1 transformations of CTU expressions may apply to expressions meeting the following criteria.

• Transformations can only apply where there is no definition status

• There must be only one focus concept

• Level 1 transformations can only apply to loose attributes (as defined above)

• When the expression contains a mixture of loose attributes and attribute groups, the attribute groups are effectively treated as for Level 1, so no transformation of these are attempted

Expression syntax, concepts being active and MRCM attribute-range validation should be applied before the transformation step. Implementations should fail fast if these are not met and not attempt transformation. This simplifies the preconditions for specific transformations.

The process of applying the transformations is iterative. This includes: collecting the set of remaining loose attributes, then applying the next transformation, and repeating until each transformation has been applied once. When each specific transformation is applied it should be greedy and transform all the loose attributes that meet the conditions of that transformation.

The list of transformations must be applied in a specific order; to ensure that the same classifiable expression is reached every time by all implementations.

The allowed patterns can be summarized as follows:

1. Refining Existing Attribute

2. Adding a Self-grouped Attribute

3. Adding Severity to Clinical Findings

4. Lateralizing Clinical Findings

The following sections elaborate on the preconditions and behaviour of each pattern.

In this case, the terminology server will accept attributes-value pairs with the following characteristics:

• The attribute is already present in the NNF of the focus concept

• The attribute value stated in the expression is a subtype of the attribute value of the focus concept

Important Notes

• If no groups are stated in the CTU expression (i.e. attributes are declared as loose attributes), the terminology server will accept attribute-value pairs correctly belonging to role groups of the focus concept as follows:

  • The terminology server will accept attribute-value pairs that refine one or more of the attribute-value pairs of the focus concept, i.e.

    • The attribute type should be the same as, or a subtype of, an attribute that already exists in the NNF of the focus concept, for which

This transformation will be applied to all loose attributes that meet the following conditions:

• The attribute applies to the MRCM domain of the focus concept (see table below)

• Only one instance of the attribute is stated in the CTU expression

  • Although the MRCM allows multiple instances, this transformation condition aims to avoid misinterpretation of the intended meaning

• Either:

Please refer to the Editorial Guide for instructions on the use and the implied meaning of these attributes:

• Clinical Finding Defining Attributes

• Procedure Defining Attributes

As part of the expression transformation process, the terminology server will place the attributes in groups on their own, as shown in the examples below.

At level 1, the terminology server will accept CTU expressions matching the following pattern:

This means that CTU expressions that includes the severity attribute will be accepted if the following criteria are met:

• The focus concept is a subtype of |Clinical finding| (but not a subtype of )

• The attribute value must be a subtype of

• When applied as a loose attribute, only one instance of the attribute may be stated in the CTU expression

• The severity attribute is not already present in the definition of the focus concept

As part of the transformation process, the terminology server will place the attribute in a group on its own, similar to the self-grouped attributes.

The terminology server will accept CTU expressions matching the following pattern:

The transformation of expressions following this pattern will include the following steps:

1. Copy the defining properties and role groups of the focus concept (as present in the NNF) to the classifiable form expression

2. Replace the value of the |Finding site| attribute with a nested expression:

From:

To:

Important Notes

When applying the concept as the value for the attribute, the transformation should be done in accordance with the modeling applied to the content in the International Edition of SNOMED CT.

This means that the transformation steps described above should be applied twice; one for each lateral half, as illustrated in the example below.

The terminology server will accept CTU expressions matching the following pattern:

The transformation of expressions following this pattern will include the following steps:

1. Copy the defining properties and role groups of the focus concept (as present in the NNF) to the classifiable form expression

2. Replace the value of the |Procedure site| attribute (or any of its subtypes / @siteAttribute) with a nested expression:

From:

To:

When applying the concept as the value for the attribute, the transformation should be done in accordance with the modeling applied to the content in the International Edition of SNOMED CT.

This means that the transformation steps described above should be applied twice; one for each lateral half, as illustrated in the example below.

At level 1, the terminology server will accept CTU expressions matching the following pattern:

This pattern allows attributes applicable to the domain to be used to add contextual information to clinical finding concepts.

The generated classifiable form must be based on the following expression with as the focus concept and the following default attributes and values unless otherwise specified by the CTU. The value of the Associated finding attribute will be replaced by the focus concept of the CF expression.

At level 1, the terminology server will accept CTU expressions matching the following pattern:

This pattern allows attributes applicable to the domain to be used to add contextual information to procedures.

The generated classifiable form must be based on the following expression with as the focus concept and the following default attributes and values, unless otherwise specified by the CTU. The value of the Associated procedure attribute will be replaced by the focus concept of the CF expression.