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Expression constraints can be built up from smaller parts using conjunction (i.e.
AND) and disjunction (i.e. OR). The simplest example of this is where the conjunction
or disjunction is used between two simple expressions. For example, the following
expression constraint is satisfied only by clinical findings which are *both* a disorder of the lung *and* an edema of the trunk. This gives the same result as a mathematical *intersection* between the set of
19829001 |Disorder of lung| descendants and the set of
301867009 |Edema of trunk| descendants.

Please note that all keywords are case insensitive, so the following two expression constraints are equivalent to the above:

The next expression constraint is satisfied only by clinical findings which are

Conjunction and disjunction operators may also be combined with the use of the 'member of' function, as shown below:

This expression constraint is satisfied only by concepts that belong to the 19829001 |Disorder of lung| hierarchy

When more than one conjunction or more than one disjunction is used, round brackets can be optionally applied. For example, the following expression constraints are all valid and equivalent to each other:

<
19829001 |Disorder of lung|
AND <
301867009 |Edema of trunk|
AND

^ 700043003 |Example problem list concepts reference set|

^ 700043003 |Example problem list concepts reference set|

(<
19829001 |Disorder of lung|
AND <
301867009 |Edema of trunk|
) AND

^ 700043003 |Example problem list concepts reference set|

^ 700043003 |Example problem list concepts reference set|

<
19829001 |Disorder of lung|
AND (<
301867009 |Edema of trunk|
AND

^ 700043003 |Example problem list concepts reference set| )

However, where a conjunction and disjunction are both used together, it is mandatory
to use round brackets to disambiguate the meaning of the expression constraint. For
example, the following expression constraint is ^ 700043003 |Example problem list concepts reference set| )

<
19829001 |Disorder of lung|
AND <
301867009 |Edema of trunk|
OR

^ 700043003 |Example problem list concepts reference set|

And must be expressed (depending on the intended meaning) as either:
^ 700043003 |Example problem list concepts reference set|

(<
19829001 |Disorder of lung|
AND <
301867009 |Edema of trunk|
) OR

^ 700043003 |Example problem list concepts reference set|

Or as:
^ 700043003 |Example problem list concepts reference set|

<
19829001 |Disorder of lung|
AND (<
301867009 |Edema of trunk|
OR

^ 700043003 |Example problem list concepts reference set| )

^ 700043003 |Example problem list concepts reference set| )

Conjunction and disjunction may be used within refinements in a variety of ways. The most common way of using these operators in a refinement is to define the conjunction or disjunction of individual attributes.

For example, the expression constraint below, in which the comma between the two attributes
represents conjunction, is satisfied only by clinical findings which have *both* a finding site of pulmonary valve structure (or subtype) *and* an associated morphology of stenosis (or subtype).

<
404684003 |Clinical finding|
:

363698007 |Finding site| = << 39057004 |Pulmonary valve structure| ,

116676008 |Associated morphology| = << 415582006 |Stenosis|

This expression constraint can equivalently be expressed as:
363698007 |Finding site| = << 39057004 |Pulmonary valve structure| ,

116676008 |Associated morphology| = << 415582006 |Stenosis|

<
404684003 |Clinical finding|
:

363698007 |Finding site| = << 39057004 |Pulmonary valve structure| AND

116676008 |Associated morphology| = << 415582006 |Stenosis|

The following example uses the disjunction operator (OR) to represent the disjunction
of two attributes. This constraint is satisfied only by clinical findings which have
363698007 |Finding site| = << 39057004 |Pulmonary valve structure| AND

116676008 |Associated morphology| = << 415582006 |Stenosis|

<
404684003 |Clinical finding|
:

116676008 |Associated morphology| = << 55641003 |Infarct| OR

42752001 |Due to| = << 22298006 |Myocardial infarction|

When more than one conjunction or more than one disjunction is used in a refinement,
round brackets can be optionally applied. For example, the following expression constraints
are all valid and equivalent to each other:
116676008 |Associated morphology| = << 55641003 |Infarct| OR

42752001 |Due to| = << 22298006 |Myocardial infarction|

<
404684003 |Clinical finding|
:

363698007 |Finding site| = << 39057004 |Pulmonary valve structure| AND

116676008 |Associated morphology| = << 415582006 |Stenosis| AND

42752001 |Due to| = << 445238008 |Malignant carcinoid tumor|

363698007 |Finding site| = << 39057004 |Pulmonary valve structure| AND

116676008 |Associated morphology| = << 415582006 |Stenosis| AND

42752001 |Due to| = << 445238008 |Malignant carcinoid tumor|

<
404684003 |Clinical finding|
:

( 363698007 |Finding site| = << 39057004 |Pulmonary valve structure| AND

116676008 |Associated morphology| = << 415582006 |Stenosis| ) AND

42752001 |Due to| = << 445238008 |Malignant carcinoid tumor|

( 363698007 |Finding site| = << 39057004 |Pulmonary valve structure| AND

116676008 |Associated morphology| = << 415582006 |Stenosis| ) AND

42752001 |Due to| = << 445238008 |Malignant carcinoid tumor|

<
404684003 |Clinical finding|
:

363698007 |Finding site| = << 39057004 |Pulmonary valve structure| AND

( 116676008 |Associated morphology| = << 415582006 |Stenosis| AND

42752001 |Due to| = << 445238008 |Malignant carcinoid tumor| )

However, where a conjunction and disjunction are both used together in a refinement,
it is mandatory to use brackets to disambiguate the meaning of the expression constraint.
363698007 |Finding site| = << 39057004 |Pulmonary valve structure| AND

( 116676008 |Associated morphology| = << 415582006 |Stenosis| AND

42752001 |Due to| = << 445238008 |Malignant carcinoid tumor| )

For example, the following expression constraint is ** not** valid:

<
404684003 |Clinical finding|
:

363698007 |Finding site| = << 39057004 |Pulmonary valve structure| AND

116676008 |Associated morphology| = << 415582006 |Stenosis| OR

42752001 |Due to| = << 445238008 |Malignant carcinoid tumor|

And must be expressed (depending on the intended meaning) as either:
363698007 |Finding site| = << 39057004 |Pulmonary valve structure| AND

116676008 |Associated morphology| = << 415582006 |Stenosis| OR

42752001 |Due to| = << 445238008 |Malignant carcinoid tumor|

<
404684003 |Clinical finding|
:

( 363698007 |Finding site| = << 39057004 |Pulmonary valve structure| AND

116676008 |Associated morphology| = << 415582006 |Stenosis| ) OR

42752001 |Due to| = << 445238008 |Malignant carcinoid tumor|

Or as:
( 363698007 |Finding site| = << 39057004 |Pulmonary valve structure| AND

116676008 |Associated morphology| = << 415582006 |Stenosis| ) OR

42752001 |Due to| = << 445238008 |Malignant carcinoid tumor|

<
404684003 |Clinical finding|
:

363698007 |Finding site| = << 39057004 |Pulmonary valve structure| AND

( 116676008 |Associated morphology| = << 415582006 |Stenosis| OR

42752001 |Due to| = << 445238008 |Malignant carcinoid tumor| )

363698007 |Finding site| = << 39057004 |Pulmonary valve structure| AND

( 116676008 |Associated morphology| = << 415582006 |Stenosis| OR

42752001 |Due to| = << 445238008 |Malignant carcinoid tumor| )

Similarly, conjunction and disjunction may be defined between attribute groups. The
following expression constraint is satisfied only by clinical findings which *either* have a finding site of pulmonary valve structure (or subtype) and an associated morphology
of stenosis (or subtype), *OR* have a finding site of right ventricular structure (or subtype) and an associated
morphology of hypertrophy (or subtype).

<
404684003 |Clinical finding|
:

{ 363698007 |Finding site| = << 39057004 |Pulmonary valve structure| ,

116676008 |Associated morphology| = << 415582006 |Stenosis| } OR

{ 363698007 |Finding site| = << 53085002 |Right ventricular structure| ,

116676008 |Associated morphology| = << 56246009 |Hypertrophy| }

{ 363698007 |Finding site| = << 39057004 |Pulmonary valve structure| ,

116676008 |Associated morphology| = << 415582006 |Stenosis| } OR

{ 363698007 |Finding site| = << 53085002 |Right ventricular structure| ,

116676008 |Associated morphology| = << 56246009 |Hypertrophy| }

Conjunction and disjunction can also be applied to attribute values. The example below
is satisfied only by members of the adverse drug reactions reference set for GP/FP
health issue, which have a causative agent that is *either* a subtype of pharmaceutical / biologic product *or* a subtype of substance.

^
450990004 |Adverse drug reactions reference set for GP/FP health issue|
:

246075003 |Causative agent| = (< 373873005 |Pharmaceutical / biologic product| OR < 105590001 |Substance| )

Similarly, attribute values can also use conjunction. The following expression constraint
is satisfied only by clinical findings with an associated morphology whose value is
246075003 |Causative agent| = (< 373873005 |Pharmaceutical / biologic product| OR < 105590001 |Substance| )

<
404684003 |Clinical finding|
:
116676008 |Associated morphology|
=

(<< 56208002 |Ulcer| AND << 50960005 |Hemorrhage| )

For more information about nested attribute values and nested compound expression
constraints, please refer to
6.7 Nested Expression Constraints.
(<< 56208002 |Ulcer| AND << 50960005 |Hemorrhage| )

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