# Evaluation of Source Meaning
The Map Terminologist will initiate the mapping process by evaluating the source SNOMED CT concept employing a context-free assumption: SNOMED CT concepts mapped are presumed to "speak for themselves". The concept definition as asserted in the Fully Specified Name (FSN) and the concept's defining relationships are presumed to encompass all information available for definition of the concept and interpreted as explained in the *SNOMED CT Editorial Guide*. This information alone will be employed by the Map Terminologist in assessing the source meaning and researching target code(s) for the Map.
If the meaning of the SNOMED CT concept is judged to be ambiguous by the Map Terminologist, the concept will be managed as follows.
## Definition of ambiguity
Two cases for concern or question of ambiguity in the SNOMED CT source concept definition will include:
* Discrepancy between the FSN and associated defining relationships.
* Discordance between the SNOMED CT definition and the term descriptions/synonyms.
Discrepancies will be assessed relative to standard medical references and compared to guidance and definitions provided in the ICD-10 authoritative source. These two cases are described in more detail below:
**Case #1** constitutes fundamental ambiguity in the meaning of the SNOMED CT concept and cannot be mapped pending clarification. These concepts will be assigned a Map member with mapCategoryId of [447640006 | Source SNOMED CT concept is ambiguous|](http://snomed.info/id/447640006) . The editorial notes field will be populated with any information on the map accrued by the Map Terminologists during their research. The concept will be referred to the SNOMED CT Editors. Once the ambiguity is resolved, the map will be completed and mapCategoryId will be updated with the appropriate assignment.
**Case #2** represents a confusing issue for the Map Terminologist using only lexical tools to review SNOMED CT and ICD-10. However, the SNOMED CT definition is not truly ambiguous, and the map for this concept will be completed as described herein. The SNOMED CT term which is the source of the confusion will be flagged by the Mapping Team in the notes for editorial review with the expectation that the confusing term will be marked for inactivation as a non-synonymous lexical tag.
Example of Case #2, discrepancy in synonyms:
* SNOMED CT [95531001 | Hemorrhagic duodenitis (disorder)|](http://snomed.info/id/95531001) has a synonym |Multiple duodenal erosions| and definition as a hemorrhagic inflammation of duodenal structure. The synonym implies ulceration and not hemorrhage and should likely be defined and classified as a type of duodenal ulcer.
|Hemorrhagic duodenitis (disorder)| maps to ICD-10 classification **K29.8 Duodenitis**. Discrepancy with concept definition will cause the map specialist to report the concept |Hemorrhagic duodenitis (disorder)| as confusing and in need of editorial review.
The context-free assumption will require agreement regarding procedures for the map when certain elements of mapping context are asserted in either the SNOMED CT source or the ICD-10 target reference. These context issues, along with mappings to multiple target codes, are detailed in the following section. In all discussions, *source* refers to the SNOMED CT concept and *target* refers to the ICD-10 classification.
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