Expression Constraint Language (ECL) High-level Reference

A brief overview of the SNOMED CT Expression Constraint Language (ECL), which is based on the post coordination syntax. The complete specification can be found at http://snomed.org/ecl.

All expression constraints are evaluated with respect to a specific version of SNOMED CT.

An expression constraint always returns a set of codes (zero or more). That is, no duplicates.

Argument Description

Argument	Description
conceptId	An SCTID optionally including a term surrounded by \| symbols. `307082005 \| Ability to process information \|`
arg	An expression or conceptId. Bracketting may be required to avoid ambiguity. `11687002` `<< 73211009` `(<< 73211009 . 363698007)`

conceptId

An SCTID optionally including a term surrounded by | symbols.

307082005 | Ability to process information |

arg

An expression or conceptId. Bracketting may be required to avoid ambiguity.

11687002

<< 73211009

(<< 73211009 . 363698007)

Category	Function	Description	Example
Basic	conceptId	The set containing the single concept with the specified conceptId.	11687002
	Any *	All active and inactive concepts.	Any *
	MemberOf conceptId ^ conceptId	The referencedComponents that are active members of the Reference Set identified by the conceptId. This may include both active and inactive concepts, but will not include concepts that were once members of the Reference Set but are no longer.	MemberOf 32570481000036109 MemberOf 32570481000036109 \|Emergency department diagnosis reference set\| ^ 32570481000036109
Hierarchy	DescendantOf conceptId DescendantOrSelfOf conceptId < conceptId << conceptId	All descendants of the concept with the specified conceptId. The `DescendantOrSelfOf` and `<<` forms also include the specified conceptId.	DescendantOf 80146002 DescendantOf 404684003 \|Clinical finding\| DescendantOrSelfOf 73211009 \|Diabetes mellitus\| < 80146002 < 404684003 \|Clinical finding\| << 73211009 \|Diabetes mellitus\|
	ChildOf conceptId ChildOrSelfOf conceptId <! conceptId <<! conceptId	The immediate children of the concept with the specified conceptId. The `ChildOrSelfOf` and `<<!` forms also include the specified conceptId.	ChildOf 404684003 ChildOrSelfOf 404684003 <! 404684003 \|Clinical finding\| <<! 404684003 \|Clinical finding\|
	AncestorOf conceptId AncestorOrSelfOf conceptId > conceptId >> conceptId	All ancestors of the concept with the specified conceptId. The `AncestorOrSelfOf` and `>>` forms also include the specified conceptId.	AncestorOf 80146002 AncestorOf 40541001 \|Acute pulmonary edema\| AncestorOrSelfOf 73211009 \|Diabetes mellitus\| > 80146002 > 40541001 \|Acute pulmonary edema\| >> 73211009 \|Diabetes mellitus\|
	ParentOf conceptId >! conceptId	The immediate parents of the concept with the specified conceptId.	ParentOf 40541001 \|Acute pulmonary edema\| >! 40541001 \|Acute pulmonary edema\|
Combined Constraints	arg AND arg	The intersection of each of the sets returned by the arguments.	174036004 AND < 80146002 < 19829001 \|Disorder of lung\| AND < 301867009 \|Edema of trunk\|
	arg OR arg	The set-union of each of the sets returned by the arguments.	11687002 OR 73211009 < 19829001 \|Disorder of lung\| OR < 301867009 \|Edema of trunk\|
	arg MINUS arg	The members of the first set that are not also in the second set.	< 73211009 MINUS 11687002 < 19829001 \|Disorder of lung\| MINUS < 301867009 \|Edema of trunk\|
Relationships	arg1 : conceptId = arg3	Attributes: All concepts matching arg1 that also have an attribute with the name matching arg2 and value matching arg3.	< 19829001 \|Disorder of lung\| : 116676008 \|Associated morphology\| = 79654002 \|Edema\| < 19829001 \|Disorder of lung\| : 116676008 \|Associated morphology\| = << 79654002 \|Edema\| < 404684003 \|Clinical finding\| : 363698007 \|Finding site\| = << 39057004 \|Pulmonary valve structure\| , 116676008 \|Associated morphology\| = << 415582006 \|Stenosis\| * : 246075003 \|Causative agent\| = 387517004 \|Paracetamol\|
	arg1 : arg2 = arg3	Attribute Operators: As above, using attribute hierarchy.	<< 404684003 \|Clinical finding\| : << 47429007 \|Associated with\| = << 267038008 \|Edema\|
	arg1 : { arg2 = arg3, arg4 = arg5 }	Attribute Groups: As above, but also respecting role grouping.	< 404684003 \|Clinical finding\| : { 363698007 \|Finding site\| = << 39057004 \|Pulmonary valve structure\| , 116676008 \|Associated morphology\| = << 415582006 \|Stenosis\| }, { 363698007 \|Finding site\| = << 53085002 \|Right ventricular structure\| , 116676008 \|Associated morphology\| = << 56246009 \|Hypertrophy\| }
	arg1 : arg2 = ( arg3 : arg4 = arg5 )	Nested Attributes: As above, but with nesting.	< 404684003 \|Clinical finding\| : 47429007 \|Associated with\| = (< 404684003 \|Clinical finding\| : 116676008 \|Associated morphology\| = << 55641003 \|Infarct\| )
	arg1 . arg2	"Reversed" Attributes: match the values of attribute arg2 for each of the concepts matching arg1	< 125605004 \|Fracture of bone\| . 363698007 \|Finding site\|
Cardinality	arg1 : [num..num] arg2 = arg3	Attribute Cardinality: As above, but with upper/lower bounds on number of attribute matches.	< 404684003 \|Clinical finding\| : [1..1] 363698007 \|Finding site\| = < 91723000 \|Anatomical structure\|