This appendix describes potential future changes designed to support template expressions. That is, expressions with predefined variables which when assigned values populate the expression.
As these are potential future extensions, this section is not a normative part of this document. It exists to gather feedback on proposed handling of template expressions. Once appropriate extensions are made to the SNOMED CT Compositional Grammar to support template extensions this section will be updated with feedback and moved to the normative part of this document.
For diagrams representing a template expression or definition, it is possible to represent "slots" which represent a placeholder a concept can fill when the template is used (see A.3). Slots are expressed using a parallelogram as shown below. The name of the slot can be considered like a variable for replacement and is surrounded by angle brackets "<" and ">".
Slots as described in section A.1 are optionally coloured with RGB FF9999 (decimal 255, 153, 153) as shown below:
Using the "slot" element described in A.1 it is possible to define diagrams that represent a template for concept definition or expressions. It is then possible to use this template to create concepts or expressions by filling the "slots" with appropriate concepts.
These template diagrams are a specialisation of concept definition diagrams as described in section 3.2; however, some of the attribute value concepts are replaced by "slots", making the definition general and reusable.
Note the names provided for the "slots" are enclosed in angle brackets "<" and ">". These slot names are inserted into the name of the concept in the top left of the diagram.
The names associated with slots operate as unique variable names for a diagram or set of diagrams. When populated, every slot with the same name on a diagram, or set of related diagrams, receives the same concept value associated with that slot name. Unless all slots names used are assigned concept values, the expression is not complete.
Earlier versions of the Diagramming Guideline included a section on providing additional context for concepts in diagrams - that is expanding concepts on diagrams to provide further information or context to a diagram.
These approaches, while potentially useful, also increase complexity and introduce the possibility of ambiguity and misinterpretation, and have therefore been omitted from the Diagramming Guideline. Feedback from readers is sought for future versions of the Diagramming Guideline, at present this appendix includes the two forms of additional context previously proposed to elicit feedback.
A concepts parents may be added to a diagram for context using "Is a" relationships as shown in section 4.2.1. For example in the following diagram the parents of 6596004 | Fracture of forearm | have been added as extra context:
Note that this in no way changes the meaning of the diagram, which represents the expression
429353004 |Injury of radius| + 65966004 |Fracture of forearm| :
{ 116676008 |Associated morphology| = 72704001 |Fracture| ,
363698007 |Finding site| = 62413002 |Bone structure of radius| }
The full definition of a concept may be added to the diagram to provide additional context for readers. Below is a diagram of the same expression used in section B.1, however this time the full definition of 6596004 | Fracture of forearm | has been provided:
A further suggested visual clarification to either approach specified in sections B.1 and B.2 is to use
a dotted/dashed box around the segments of the diagram providing "additional context"
and/or change connectors in segments reflecting "additional context" to use dotted or dashed lines
Is a complementary, not a competing, proposal to those specified in sections B.1 and B.2.
Diagram Types explores three different forms of diagram for expressing
Expressions
Concept definition
Expression relation
This appendix explores a fourth type of diagram, essentially an extended use of the "Concept definition" diagram for use specifically in rendering interactive diagrams to navigate and explore SNOMED CT content.
This specific case is not included in the formal Diagramming Guideline at present, as it requires further exploration to be specified. However it may also be determined that there are multiple differing renderings that are useful in different browsing scenarios, and therefore one or a finite number of diagram styles may not be possible to define.
The following sections and examples are intended to demonstrate alternate layouts useful for browsing use cases, in an effort to elicit feedback and explore this scenario.
Figure Appendix C-1: depicts a concept definition diagram as used in the Workbench Utilities at the time of writing.
The most distinguishing feature of this approach is the removal of the "equivalence" symbol as an abbreviation. This enables the concept's parents to appear above the "concept in focus" while attributes appear on the right without excess clutter (as depicted in Figure 31).
Note that this diagram also includes child concepts of the "concept in focus" below, and attributes of which the "concept in focus" is a target on the left. This results in
The arrows emanating from the "concept in focus" showing the definition of the "concept in focus"
The arrows entering the "concept in focus" showing where the "concept in focus" is used in the definition of other concepts.
Figure Appendix C-3: depicts an alternate representation to that shown in Figure 30, where the "equivalence" symbol has not been abbreviated.
This approach is it conforms to the concept definition form in section 3.2; however it does present a more cluttered diagram than the abbreviated form in Figure 30.
Figure Appendix C-5: shows an alternative layout of Figure 31. This layout uses the same layout used in 3.2 for the definition of the "concept in focus" - parent concepts shown on the right hand side.
This is matches the representation in 3.2, and achieves more space for rendering where the "concept in focus" is used in the definition of other concepts. However the resulting diagram is less intuitive than displaying the focus concept's parents above the focus concept.
The diagram options in this appendix have been largely focussed on a concept definition centric interaction/navigation; however there are other focuses that may also be useful.
For example it is common to consider browsing or navigating SNOMED CT purely from its sub/supertype relationships in a full hierarchical view back to the root node. While the examples in this section do provide immediate parents, sometimes hierarchical views showing full lineage are useful. However given the real-estate requirements of full lineage and full concept definition, it is unlikely that both renderings can coexist on the same diagram concurrently. Consequently an alternate style may be required for this view, of which there are many examples in SNOMED CT browsers at present.
Another example scenario is browsing a reference set/s or SNOMED CT content in context of a reference set/s. Again this use case is likely sufficiently at odds with the examples provided in this appendix that an alternate diagram style is required.
As this Diagramming Guideline is focussed on expressions and concept definitions, these and other potential views are out of scope and as yet unexplored formally by this document. Many examples of these renderings exist in the numerous SNOMED CT browsers, and may be left unspecified for the continued innovation of browser vendors, or explored in future versions of the Diagramming Guidelines if considered worthwhile.
The following diagrams show examples taken from the SNOMED CT Technical Implementation Guide January 2013, redrawn using the notation specified in this document. If approved it is anticipated that the diagrams in the SNOMED CT Technical Implementation Guide would be replaced by the examples shown in this section.
For convenience the figure number and original diagram from the SNOMED CT Technical Implementation Guide have been included in this section.
Note that the diagrams drawn in this section are an exact copy of the diagrams from the SNOMED CT Technical Implementation Guide as at January 2013. Some of the concepts represented in the diagrams do not appear in the actual SNOMED CT January 2013 content; however this has been faithfully copied from the current diagrams in the SNOMED CT Technical Implementation Guide.
Figure 21: Refining a concept to add specificity from the SNOMED CT Technical Implementation Guide section 4.2.2.3.3
Would be redrawn as
Note that the redrawn expression diagram is distinguishable from a concept definition of "hand pain" - under the notation specified in this document concept definitions are rendered differently.
Figure Appendix D-3: Nested refinement applied to a body site from the SNOMED CT Technical Implementation Guide section 4.2.2.3.3
Would be redrawn as
Figure Appendix D-6: Grouped refinement from the SNOMED CT Technical Implementation Guide section 4.2.2.3.3
Would be redrawn as
Figure Appendix D-9: An expression with two focus concepts from the SNOMED CT Technical Implementation Guide section 4.2.2.3.4
Would be redrawn as
Figure 25 An alternative view of an expression with two focus concepts from the SNOMED CT Technical Implementation Guide section 4.2.2.3.4
Figure Appendix D-13: Would be drawn little different to the previous example for Figure 24 An expression with two focus concepts as
Figure 26 Family history of a specific type of severe allergy to nuts as close-to-user form expression from the SNOMED CT Technical Implementation Guide section 4.2.2.3.5
Would be redrawn as
Figure 27 Family history of severe allergy to nuts represented by using a context wrapper expression from the SNOMED CT Technical Implementation Guide section 4.2.2.3.5
Would be redrawn as
