SNOMED CT® Release Format 1 (RF1) Guide - ihtsdo

230 | SNOMED CT Release Format 1 (RF1) Guide July 2012
11. A Cross Map Target contains a set of one or more codes in the Target Scheme.
Figure 42: A logical model of the cross mapping process
3.2.11.7.1. Simple one-to-one mapping
One-to-one mapping between a selected SNOMED CT Concept and single Target Code is possible in some
cases.
This is represented by a single Cross Map, which is associated with the Concept and is a member of the
Cross Map Set associated with that Target Scheme.The Cross Map refers to a Cross Map Target that contains
only one Target Code.
3.2.11.7.2. Simple one-to-many mapping
One-to-many mapping between a selected SNOMED CT Concept and set of more than one Target Codes
is required for Target Schemes that use combinations of codes to express the same meaning as a single
SNOMED CT Concept.
This is represented by a single Cross Map, which is associated with the Concept and is a member of the
Cross Map Set associated with that Target Scheme.The Cross Map refers to a Cross Map Target that contains
two or more Target Codes.
3.2.11.7.3. Mapping with options
Mapping with options is required where there are several possible ways of mapping a Concept into the Target
Scheme.
Multiple options may occur in two circumstances:
• The Target Scheme provides more detailed representation than is offered by the SNOMED CT Concept.
This may occur with SNOMED CT Concepts that are mappable if qualified in some way:
• If the qualification required is an associated qualifying Concept or an associated numeric value then
automated mapping is feasible;
• If the qualification is provided as free text then manual intervention will be required but may be assisted
by providing appropriate advice.
• The Target Scheme encodes the Concept in a manner that includes other related information about the
patient. Examples of this include:
• Classifications that subdivide disorders by age, sex or other patient characteristics;
• Groupers that encode combinations of procedures and disorders;
• Use of patient record context or links between statements to indicate suspected causation or other
clinically significant relationships.
These requirements are represented by multiple Cross Maps associated with a single Concept with the Cross
Map Set associated with the Target Scheme.
• The Concept for which Cross Maps are sought is the primary Concept of a selected Statement in the
patient record.
• Where multiple maps are found, the rules in these Cross Maps are processed to determine which of the
maps is appropriate. These rules may refer to:
• Qualifications of the selected Statement.
• Other Statements (including relevant qualifications) that are:
• Explicitly related to the selected Statement (e.g. a treatment specifically undertaken for a particular
condition).
• In the same complex as the selected Statement (e.g. another diagnosis during the same episode
or admission).
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