...

Description filter constraints provide the ability the ability to limit the set of concepts, that satisfy a given expression constraint, based on the descriptions associated with each concept. Only concepts that have at least one matching description for each filter criteria will be included in the set of matching concepts. Descriptions can be filtered based on their term, type, language, dialect, acceptability in a given dialect, module, effectiveTime and , active status and description identifier.  Description filters are specified inside double curly braces, and optionally being with the letter "D". Any filter that does not specify its type is, by default, assumed to be a description filter.

...

Term filters enable an expression constraint to match on only those concepts with an associated description whose term matches the given search term. For example, the following expression constraint is satisfied by SNOMED CT concepts with a description matching the search terms "heart" and "att". This expression constraint works like a term search performed in a SNOMED CT browser. Please note that the "D" (either upper or lower case) at the start of the filter indicates that this is a description filter constraint, rather than a concept filter constraint (see see 6.9 Concept Filter ConstraintsFilters). If the type of a filter constraint is not specified (as in most of the examples below), then it is assumed that the constraint is a description constraint.

...

< 64572001 |Disease| {{ term = ("heart" "card")}}

The other match technique that may be used is a wildcard matchsearch.  This uses an technique is specified using the keyword "wild:" and matches the search term in the expression constraint against the entire candidate description term (rather than just individual words).  An asterisk ('*') is used as a wildcard to indicate that any (zero to many) characters may appear in the given position, and is specified using the keyword "wild:" before the search term..

For example, the expression For example, the expression constraint below will match only diseases with a description term starting with "cardi" and ending with "opathy" with any number of characters between. This term filter would therefore match on terms such as "cardiopathy", "cardiomyopathy" and "cardiac channelopathy", but would not match on terms like "atrial cardiopathy" or "Cardiomyopathy (disorder)".

...

< 64572001 |Disease| {{ term = wild:"cardi*opathy"}}

It is also possible to mix the match techniques in a search term setPlease note that to perform an exact string match on an entire term, a wildcard search without a wildcard can be used (e.g. term=wild:"cardiopathy"). For example, the following expression constraint below will match those only diseases with a description term that either contains a word starting with "gas", or ending with "itis" - e.g. "gastric flu", "gastritis", or "tonsillitis".

< 64572001 |Disease| {{ term = (match:"gas" wild:"*itis")}}

If more than one filter is applied, then all filters (surrounded in double braces) must match at least one description of a concept, for that concept to satisfy the constraint. The descriptions that match each of the filters can either be the same description, or different descriptions on the same concept.

exactly matches the full string "cardiopathy". This expression constraint will therefore match the concept 

< 64572001 |Disease| {{ term = wild:"cardiopathy"}}

It is also possible to mix the match techniques in a search term set. For example, the expression constraint below will match those diseases with a description term that either contains a word starting with "gas", or ending with "itis" - e.g. "gastric flu", "gastritis", or "tonsillitis".

< 64572001 |Disease| {{ term = (match:"gas" wild:"*itis")}}

If more than one filter is applied, then all filters (surrounded in double braces) must match at least one description of a concept, for that concept to satisfy the constraint. The descriptions that match each of the filters can either be the same description, or different descriptions on the same concept.

The expression constraint below matches those diseases which have both a description that contains a word starting "eye" and a description that ends with "itis". For example, this constraint would match the concept 

...

And the following expression constraints return all concepts in the International Patient Summary reference set, which have an inactive descriptioninactive description.

^ 816080008 |International Patient Summary| {{ D active = 0 }}

^ 816080008 |International Patient Summary| {{ D active = false }}

Description Id Filter

Description id filters enable an expression constraint to match on only those concepts with a description that has a matching description identifier. For example, the following expression constraint matches any concept, which has an associated description with the identifier "3032638017". The only concept that matches this expression constraint is

* {{ D id = 3032638017 }}

Description id filters can also be applied to other expression constraints, to check whether the concept with the matching description id is in a given set of concepts. For example, the following expression constraint will match any descendant of

< 195967001 |Asthma (disorder)| {{ D id = 3032638017 }}

Description id filters may also include a set of description identifiers. The following expression constraint will match any descendant of

< 195967001 |Asthma (disorder)| {{ D id = (1208972017 2674140012 3043971012) }}

Please note that inactive concepts can have active descriptions, so the description id filter can be applied after inactive concepts are added to the query results via a history supplement. For example, the following expression constraint matches any descendant of the concept

^(< 816080008195967001 |International Patient SummaryAsthma (disorder)| {{ D active = 0 }}

^ 816080008 |International Patient Summary| +HISTORY}}) {{ D activeid = false264553015 }}

For more information on history supplements, please refer to 6.11 History Supplements.