This page is part of the FHIR Specification (v1.6.0: STU 3 Ballot 4). The current version which supercedes this version is 5.0.0 . For a full list of available versions, see the Directory of published versions . For a full list of available versions, see the Directory of published versions . Page versions: . Page versions: R5 R4B R4 R3 R2

2.13.1 5.1.1 Slicing and Discriminator Examples Slicing and Discriminator Examples

FHIR Infrastructure FHIR Infrastructure Work Group Work Group

Maturity Level : N/A Maturity Level : N/A

Ballot Status : DSTU 2 Ballot Status : STU 3

2.13.1.1 Slicing Patient Contact Details 5.1.1.1 Slicing Patient Contact Details One common use of slicing is to describe different constraints on different kinds of patient contact details. In this example, as Patient.telecom is defined as: ContactPoint [0..*] where the ContactPoint has system, value and use. Consider the case where the profile should say: There must be a single home phone number The patient may have a work phone number The patient may have an email address No other types of contact are allowed An example of a patient resource that meets these rules:

One common use of slicing is to describe different constraints on different kinds of patient contact details. In this example, as Patient.telecom is defined as: ContactPoint [0..*] where the ContactPoint has system, value and use.

Consider the case where the profile should say:

• There must be a single home phone number
• The patient may have a work phone number
• The patient may have an email address
• No other types of contact are allowed

An example of a patient resource that meets these rules:

<Patient>                         
... snip ...
  <telecom>                       
    <system value="phone" />      
    <use value="home" />          
    <value value="5551234567" />  
  </telecom>
  <telecom>                       
    <system value="email" />      
    <value value="someone@acme.org" />  
  </telecom>
... snip ...
</Patient>
To
do
this,
the
profile
that
implements
these
rules
needs
to
do
the
following:
On
the
base
Patient.telecom
element:
define
that
slicing
is
discriminated
by
system
and
use,
and
that
the
slices
are
closed
("No
other
types
of
contact
are
allowed").
Order
is
left
unfixed
Then
define
3
slices:
home
phone:
fixed
values
for
system
and
use,
and
cardinality
1..1
work
phone:
fixed
values
for
system
and
use,
and
cardinality
0..1
email:
fixed
value
for
system,
cardinality
0..0
for
use,
and
cardinality
0..1
In
a
StructureDefinition,
this
will
look
like:

To do this, the profile that implements these rules needs to do the following:

• On the base Patient.telecom element: define that slicing is discriminated by system and use, and that the slices are closed ("No other types of contact are allowed"). Order is left unfixed
• Then define 3 slices:
  1. home phone: fixed values for system and use, and cardinality 1..1
  2. work phone: fixed values for system and use, and cardinality 0..1
  3. email: fixed value for system, cardinality 0..0 for use, and cardinality 0..1

In a StructureDefinition, this will look like:

  <!-- setting up the slicing -->
  <element> 
    <path value="Patient.telecom"/>
    <slicing>
      <discriminator value="system"/>
      <discriminator value="use"/>
      <rules value="closed"/>
    </slicing>
    <!-- net cardinality rules -->
    <min value="1"/>
    <max value="3"/>
  </element>
  
  <!-- first slice: home phone -->
  <element> 
    <path value="Patient.telecom"/>
    <name value="HomePhone"/> <!-- mandatory - gives the slice a name -->
    <min value="1"/>
    <max value="1"/>
  </element>
  <element> 
    <path value="Patient.telecom.system"/>
    <min value="1"/>
    <fixedCode value="phone"/>
  </element>
  <element> 
    <path value="Patient.telecom.value"/>
    <min value="1"/>
  </element>
  <element> 
    <path value="Patient.telecom.use"/>
    <min value="1"/>
    <fixedCode value="home"/>
  </element>
  
  <!-- second slice: work phone -->
  <element> 
    <path value="Patient.telecom"/>
    <name value="WorkPhone"/> <!-- mandatory - gives the slice a name -->
    <min value="0"/>
    <max value="1"/>
  </element>
  <element> 
    <path value="Patient.telecom.system"/>
    <min value="1"/>
    <fixedCode value="phone"/>
  </element>
  <element> 
    <path value="Patient.telecom.value"/>
    <min value="1"/>
  </element>
  <element> 
    <path value="Patient.telecom.use"/>
    <min value="1"/>
    <fixedCode value="work"/>
  </element>
  
  <!-- third slice: email -->
  <element> 
    <path value="Patient.telecom"/>
    <name value="Email"/> <!-- mandatory - gives the slice a name -->
    <min value="0"/>
    <max value="1"/>
  </element>
  <element> 
    <path value="Patient.telecom.system"/>
    <min value="1"/>
    <fixedCode value="email"/>
  </element>
  <element> 
    <path value="Patient.telecom.value"/>
    <min value="1"/>
  </element>
  <element> 
    <path value="Patient.telecom.use"/>
    <min value="0"/>
  </element>
Note:
lots
of
definition
detail
has
been
left
out,
and
only
the
parts
relevant
to
the
pattern
are
shown.
Also,
providing
a
fixed
value
makes
the
minimum
cardinality
irrelevant,
but
it
is
shown
here
for
completeness.
This
table
illustrates
the
relationship
between
the
instance
and
the
ElementDefinitions:

Note: lots of definition detail has been left out, and only the parts relevant to the pattern are shown. Also, providing a fixed value makes the minimum cardinality irrelevant, but it is shown here for completeness.

This table illustrates the relationship between the instance and the ElementDefinitions:

2.13.1.2 Blood Pressure Example 5.1.1.2 Blood Pressure Example Another use of Slicing is for Blood Pressure Measurements, where the profile says: There must be two components The first has LOINC code 8480-6, and a quantity The second has LOINC code 8462-4, and a quantity Other components are allowed (posture, etc., but not profiled in the base blood pressure profile) An example of an Observation resource that meets these rules:

Another use of Slicing is for Blood Pressure Measurements, where the profile says:

• There must be two components
• The first has LOINC code 8480-6, and a quantity
• The second has LOINC code 8462-4, and a quantity
• Other components are allowed (posture, etc., but not profiled in the base blood pressure profile)

An example of an Observation resource that meets these rules:

<Observation>                         
... snip ...
  <component>                       
    <code>                       
      <coding>                       
        <system value="http://loinc.org" />      
        <code value="8480-6" />  
        <display value="Systolic blood pressure" />  
      </coding>                       
    </code>                       
    <valueQuantity>                       
      <value value="120" />  
      <unit value="mmHg" />  
      <system value="http://unitsofmeasure.org" />  
      <code value="mm[Hg]" />  
    </valueQuantity>                       
  </component>
  <component>                       
    <code>                       
      <coding>                       
        <system value="http://loinc.org" />      
        <code value="8462-4" />  
        <display value="Diastolic blood pressure" />  
      </coding>                       
    </code>                       
    <valueQuantity>                       
      <value value="80" />  
      <unit value="mmHg" />  
      <system value="http://unitsofmeasure.org" />  
      <code value="mm[Hg]" />  
    </valueQuantity>                       
  </component>
</Patient>
To
do
this,
the
profile
that
implements
these
rules
needs
to
do
the
following:
On
the
base
Observation.component
element:
define
that
slicing
is
discriminated
by
code.
Order
is
left
unfixed,
and
rules
left
open.
Then
define
2
slices:
systolic:
fixed
values
for
code,
cardinality
1..1,
value
is
a
Quantity
diastolic:
fixed
values
for
code,
cardinality
1..1,
value
is
a
Quantity
In
a
StructureDefinition,
this
will
look
like:

To do this, the profile that implements these rules needs to do the following:

• On the base Observation.component element: define that slicing is discriminated by code. Order is left unfixed, and rules left open.
• Then define 2 slices:
  1. systolic: fixed values for code, cardinality 1..1, value is a Quantity
  2. diastolic: fixed values for code, cardinality 1..1, value is a Quantity

In a StructureDefinition, this will look like:

  <!-- setting up the slicing -->
  <element> 
    <path value="Observation.component"/>
    <slicing>
      <discriminator value="code"/>
    </slicing>
    <!-- net cardinality rules -->
    <min value="2"/>
    <max value="*"/>
  </element>
  
  <!-- first slice: systolic -->
  <element> 
    <path value="Observation.component"/>
    <name value="systolic"/> <!-- mandatory - gives the slice a name -->
    <min value="1"/>
    <max value="1"/>
  </element>
  <element> 
    <path value="Observation.component.code"/>
    <min value="1"/>
    <fixedCodeableConcept>
      <coding>                       
        <system value="http://loinc.org" />      
        <code value="8480-6" />  
        <display value="Systolic blood pressure" />  
      </coding>                       
    </fixedCodeableConcept>
  </element>
  <element> 
    <path value="Observation.component.valueQuantity"/>
    <min value="1"/>
  </element>
  
  <!-- second slice: diastolic -->
  <element> 
    <path value="Observation.component"/>
    <name value="diastolic"/> <!-- mandatory - gives the slice a name -->
    <min value="1"/>
    <max value="1"/>
  </element>
  <element> 
    <path value="Observation.component.code"/>
    <min value="1"/>
    <fixedCodeableConcept>
      <coding>                       
        <system value="http://loinc.org" />      
        <code value="8462-4" />  
        <display value="Diastolic blood pressure" />  
      </coding>                       
    </fixedCodeableConcept>
  </element>
  <element> 
    <path value="Observation.component.valueQuantity"/>
    <min value="1"/>
  </element>
Note:
lots
of
definition
detail
has
been
left
out,
and
only
the
parts
relevant
to
the
pattern
are
shown.
E.g.
A
real
blood
pressure
profile
would
fix
unit,
a
overall
Observation
code
etc.

Note: lots of definition detail has been left out, and only the parts relevant to the pattern are shown. E.g. A real blood pressure profile would fix unit, a overall Observation code etc.

2.13.1.3 Extensions 5.1.1.3 Extensions For another example, consider slicing extensions. The base extension on every element is defined as a list (0..*) of extensions, and each extension has a url that identifies it, and a value. Consider an example where a profile defines that for a particular element (named Patient), there are two extensions, with URLs http://acme.com/a and http://acme.com/b. In addition, the profile allows other extensions to be used. Technically, the profile achieves this by "slicing" the extension list, into two slices, and saying that the slicing is "open" - that there can be other slices introduced. Here are the relevant parts of the Profile on patient:

For another example, consider slicing extensions. The base extension on every element is defined as a list (0..*) of extensions, and each extension has a url that identifies it, and a value. Consider an example where a profile defines that for a particular element (named Patient), there are two extensions, with URLs http://acme.com/a and http://acme.com/b. In addition, the profile allows other extensions to be used.

Technically, the profile achieves this by "slicing" the extension list, into two slices, and saying that the slicing is "open" - that there can be other slices introduced. Here are the relevant parts of the Profile on patient:

<StructureDefinition xmlns="http://hl7.org/fhir">
  <!-- snip -->
    <constrainedType value="Patient"/>

    <baseType value="Patient" />
    <baseDefinition value="http://hl7.org.fhir/StructureDefinition/Patient" />
    <derivation value="constraint" />

    <snapshot>
      <element>
        <path value="Patient"/>
        <!-- snip -->
      </element>
      <element>
        <path value="Patient.extension"/>
        <!-- this first element defines the slicing, and carries the base definition forward -->
        <slicing>
          <discriminator value="url"/> <!-- Extensions are always discriminated by URL -->
          <ordered value="false"/>     <!-- we don't care what order they appear in -->
          <rules value="open"/>        <!-- other extensions can be used -->
        </slicing>
        <!-- -- snip definition -->
      </element>
      <!-- first extension -->
      <element>
        <path value="Patient.extension"/>
        <!-- snip most of definition -->
        <type>
         <code value="Extension"/>
         <!-- the profile for an extension is a reference to the extension definition itself -
           this implies a profile, and happens to fix the @url value to the desired URL -->
         <profile value="http://acme.com/a"/>
        </type>
      </element>
      <!-- second extension -->
      <element>
        <path value="Patient.extension"/>
        <!-- snip most of definition -->
        <type>
         <code value="Extension"/>
         <!-- the profile for an extension is a reference to the extension definition itself -
           this implies a profile, and happens to fix the @url value to the desired URL -->
         <profile value="http://acme.com/b"/>
        </type>
      </element>
      <!-- snip rest of profile -->
    </snapshot>
</StructureDefinition>
Here's
a
patient
example
that
conforms
to
this
profile:

Here's a patient example that conforms to this profile:

<Patient xmlns="http://hl7.org/fhir">
  <!-- two extensions, the order doesn't matter -->
  <extension url="http://acme.com/b">
    <!-- this has the right url, and so matches the second slice -->
    <!-- snip whatever value extension would have -->
  </extension>
  <extension url="http://acme.com/a">
    <!-- this has the right url, and so matches the first slice -->
    <!-- snip whatever value extension would have -->
  </extension>
  <!-- the rest of patient -->
</Patient>

2.13.1.4 Diagnostic Report & Observation 5.1.1.4 Diagnostic Report & Observation In this example, a profile on an diagnostic report says that it must have 4 observations, each with a different LOINC code (e.g. a classic lab panel). In this case (taken from the Example Lipid Profile

In this example, a profile on an diagnostic report says that it must have 4 observations, each with a different LOINC code (e.g. a classic lab panel). In this case (taken from the Example Lipid Profile ), the structure that applies to DiagnosticReport will say that there are 4 slices on DiagnosticReport.result, each conforming to a different structure, which are also contained in the same profile. Each of those structures will constrain the LOINC code in the observation. ), the structure that applies to DiagnosticReport will say that there are 4 slices on DiagnosticReport.result, each conforming to a different structure, which are also contained in the same profile. Each of those structures will constrain the LOINC code in the observation.

<!-- first structure, the DiagnosticReport -->
<StructureDefinition xmlns="http://hl7.org/fhir">
  <!-- snip -->
  <url value="http://acme.org/fhir/StructureDefinition/lipid-report"/>
  <constrainedType value="DiagnosticReport"/>
  <base value="http://hl7.org/fhir/StructureDefinition/DiagnosticReport"/>

  <name value="LipidProfile"/>
  <baseType value="DiagnosticReport"/>
  <baseDefinition value="http://hl7.org/fhir/StructureDefinition/DiagnosticReport"/>
  <derivation value="constraint" />


  <!-- snip -->
  <snapshot>
    <!-- snip elements -->
    <element>
      <!-- first definition for result -->
      <path value="DiagnosticReport.result"/>
      <slicing>
        <!-- this is sliced by the code value of the target of the reference -->
        <discriminator value="reference.code"/>
        <!-- have to be in the specified order -->
        <ordered value="true"/>
        <!-- this profile says, no other observations allowed -->
        <rules value="closed"/>
      </slicing>
      <!-- snip definition -->
    </element>
    <!-- first slice: Cholesterol -->
    <element>
      <path value="DiagnosticReport.result"/>
      <name value="Cholesterol"/>
      <!-- snip definition parts -->
      <type>
        <code value="Reference"/>
        <!-- this element must conform to the "Cholesterol" structure -->
        <profile value="http://acme.org/fhir/StructureDefinition/Cholesterol"/>
      </type>
    </element>
    <!-- next 3 slices all the same, but different names for profile -->
    <element>
      <path value="DiagnosticReport.result"/>
      <name value="Triglyceride"/>
      <!-- snip definition parts -->
      <type>
        <code value="Reference"/>
        <!-- this element must conform to the "Triglyceride" structure -->
        <profile value="http://acme.org/fhir/StructureDefinition/Triglyceride"/>
      </type>
    </element>
    <element>
      <path value="DiagnosticReport.result"/>
      <name value="LDLCholesterol"/>
      <!-- snip definition parts -->
      <type>
        <code value="Reference"/>
        <!-- this element must conform to the "LDLCholesterol" structure -->
        <profile value="http://acme.org/fhir/StructureDefinition/LDLCholesterol"/>
      </type>
    </element>
    <element>
      <path value="DiagnosticReport.result"/>
      <name value="HDLCholesterol"/>
      <!-- snip definition parts -->
      <type>
        <code value="Reference"/>
        <!-- this element must conform to the "HDLCholesterol" structure -->
        <profile value="http://acme.org/fhir/StructureDefinition/HDLCholesterol"/>
      </type>
    </element>
    <!-- snip elements -->
  </snapshot>
</StructureDefinition>

<!-- now, the second structure, for the Cholesterol profile -->
<StructureDefinition>
  <url value="http://acme.org/fhir/StructureDefinition/Cholesterol"/>
  <constrainedType value="Observation"/>
  <base value="http://hl7.org/fhir/StructureDefinition/Observation"/>

  <name value="Cholesterol"/> 
  <baseType value="Observation"/>
  <baseDefinition value="http://hl7.org/fhir/StructureDefinition/Observation"/>
  <derivation value="constraint" />

  <snapshot>
    <!-- snip elements -->
    <element>
      <!-- this the element definition for name. Because of the
        slicing / discriminator rules in the LipidReport profile
        that references it, it is required to fix the value of
        the name element -->
      <path value="Observation.code"/>
      <definition>
         <!-- there are actually 3 ways to fix a CodeableConcept
         to a single fixed value. Here, we used the simplest one -->
         <valueCodeableConcept>
           <!-- just fix the value to the right code -->
           <coding>
             <system value="http://loinc.org"/>
             <code value="35200-5"/>
             <display value="Cholesterol"/>
           </coding>
         </valueCodeableConcept>
      </definition>
    </element>
    <!-- snip elements -->
  </snapshot>
</StructureDefinition>

<!-- Triglyceride profile -->
<StructureDefinition>
  <url value="http://acme.org/fhir/StructureDefinition/Triglyceride"/>
  <constrainedType value="Observation"/>
  <base value="http://hl7.org/fhir/StructureDefinition/Observation"/>

  <name value="Triglyceride"/> 
  <baseType value="Observation"/>
  <baseDefinition value="http://hl7.org/fhir/StructureDefinition/Observation"/>
  <derivation value="constraint" />

  <snapshot>
    <!-- snip elements -->
    <element>
      <!-- this the element definition for name. Because of the
        slicing / discriminator rules in the LipidReport profile
        that references it, it is required to fix the value of
        the name element -->
      <path value="Observation.code"/>
      <definition>
         <!-- there's actually 3 ways to fix a CodeableConcept
         to a single fixed value. Here, we used the simplest one -->
         <valueCodeableConcept>
           <!-- just fix the value to the right code -->
           <coding>
             <system value="http://loinc.org"/>
             <code value="35217-9"/>
             <display value="Triglyceride"/>
           </coding>
         </valueCodeableConcept>
      </definition>
    </element>
    <!-- snip elements -->
  </snapshot>
</StructureDefinition>

<!-- LDLCholesterol profile -->
<StructureDefinition>
  <url value="http://acme.org/fhir/StructureDefinition/LDLCholesterol"/>
  <constrainedType value="Observation"/>
  <base value="http://hl7.org/fhir/StructureDefinition/Observation"/>

  <name value="LDLCholesterol"/> 
  <baseType value="Observation"/>
  <baseDefinition value="http://hl7.org/fhir/StructureDefinition/Observation"/>
  <derivation value="constraint" />

  <snapshot>
    <!-- snip elements -->
    <element>
      <!-- this the element definition for name. Because of the
        slicing / discriminator rules in the LipidReport profile
        that references it, it is required to fix the value of
        the name element -->
      <path value="Observation.code"/>
      <definition>
         <!-- because of the way that LDL cholesterol measurements works
           (well, in this context- it varies), there's 2 different LOINC
           codes for either measured or calculated. So here, we bind to
           a value set -->
       <binding>
        <conformance value="required"/> <!-- must be required if this is a discriminator -->
        <!-- snip the actual value set reference, but it refers to a value
             set with two LOINC codes, one for each kind of LDL, which in
             this case are LOINC codes 18262-6 and 13457-7 -->
       </binding>
     </definition>
    </element>
    <!-- snip elements -->
  </snapshot>
</StructureDefinition>

<!-- HDLCholesterol profile -->
<StructureDefinition>
  <url value="http://acme.org/fhir/StructureDefinition/HDLCholesterol"/>
  <constrainedType value="Observation"/>
  <base value="http://hl7.org/fhir/StructureDefinition/Observation"/>

  <name value="HDLCholesterol"/> 
  <baseType value="Observation"/>
  <baseDefinition value="http://hl7.org/fhir/StructureDefinition/Observation"/>
  <derivation value="constraint" />

  <snapshot>
    <!-- snip elements -->
    <element>
      <!-- this the element definition for name. Because of the
        slicing / discriminator rules in the LipidReport profile
        that references it, it is required to fix the value of
        the name element -->
      <path value="Observation.code"/>
      <definition>
         <!-- there's actually 3 ways to fix a CodeableConcept
         to a single fixed value. Here, we used the simplest one -->
         <valueCodeableConcept>
           <!-- just fix the value to the right code -->
           <coding>
             <system value="http://loinc.org"/>
             <code value="2085-9"/>
             <display value="LDL Cholesterol"/>
           </coding>
         </valueCodeableConcept>
      </definition>
    </element>
    <!-- snip elements -->
  </snapshot>
</StructureDefinition>

Here
is
an
instance
that
meets
the
rules
for
this
profile:

Here is an instance that meets the rules for this profile:

<!-- first, the diagnostic report -->
<DiagnosticReport xmlns="http://hl7.org/fhir">
  <!-- snip -->
  <!-- here's the set of results. We don't know what
    slices they are or anything until we go off, find
    the references, and look in them -->
  <result>
    <reference value="Observation/cholesterol"/>
  </result>
  <result>
    <reference value="Observation/triglyceride"/>
  </result>
  <result>
    <reference value="Observation/ldlcholesterol"/>
  </result>
  <result>
    <reference value="Observation/hdlcholesterol"/>
  </result>
  <!-- snip -->
</DiagnosticReport>

<!-- Observation, id = cholesterol -->
<Observation xmlns="http://hl7.org/fhir">
  <!-- the observation starts with the name, as specified
    by the profile for the first slice  -->
  <code>
    <coding>
      <system value="http://loinc.org"/>
      <code value="35200-5"/>
      <display value="Cholesterol"/>
    </coding>
  </code>
  <!-- snip -->
</Observation>

<!-- Observation, id = triglyceride -->
<!-- this code matches the second slice. good -->
<Observation xmlns="http://hl7.org/fhir">
  <code>
    <coding>
      <system value="http://loinc.org"/>
      <code value="35217-9"/>
      <display value="Triglyceride"/>
    </coding>
  </code>
  <!-- snip -->
</Observation>

<!-- Observation, id = hdlcholesterol -->
<!-- this code matches the fourth slice. good -->
<Observation xmlns="http://hl7.org/fhir">
  <code>
    <coding>
      <system value="http://loinc.org"/>
      <code value="2085-9"/>
      <display value="HDL Cholesterol"/>
    </coding>
  </code>
  <!-- snip -->
</Observation>

<!-- Observation, id = ldlcholesterol -->
<!-- this code matches the third slice. good -->
<Observation id="ldlcholesterol">
  <code>
    <coding>
      <system value="http://loinc.org"/>
      <code value="13457-7"/>
      <display value="LDL Chol. (Calc)"/>
    </coding>
  </code>
  <!-- snip -->
</Observation>
Note
that
this
version
isn't
valid,
because
the
slices
are
not
in
the
correct
order:

Note that this version isn't valid, because the slices are not in the correct order:

<!-- first, the diagnostic report -->
<DiagnosticReport xmlns="http://hl7.org/fhir">
  <!-- snip -->
  <!-- here's the set of results. We don't know what
    slices they are or anything until we go off, find
    the references, and look in them -->
  <result>
    <reference value="Observation/cholesterol"/>
  </result>
  <result>
    <reference value="Observation/triglyceride"/>
  </result>
  <result>
    <reference value="Observation/hdlcholesterol"/>
  </result>
  <result>
    <reference value="Observation/ldlcholesterol"/>
  </result>
  <!-- snip -->
</DiagnosticReport>

2.13.1.5 Composition Sections 5.1.1.5 Composition Sections Most uses of Composition involve conformance to a profile that specifies which sections will exist, and what their contents will be. This is yet another example of slicing. A typical document content profile might specify a section structure something like this: Reason for visit Narrative, LOINC Code 29299-5 Medications, LOINC Code 46057-6 Prescribed Medications, LOINC Code 66149-6 OTC medications, 66150-4 (optional) Vital Signs, LOINC Code 8716-3 Real profiles will contain lots of detail about the sections, but these are omitted here in the interests of clarity. An example of a Composition that meets these rules:

Most uses of Composition involve conformance to a profile that specifies which sections will exist, and what their contents will be. This is yet another example of slicing. A typical document content profile might specify a section structure something like this:

• Reason for visit Narrative, LOINC Code 29299-5
• Medications, LOINC Code 46057-6
  • Prescribed Medications, LOINC Code 66149-6
  • OTC medications, 66150-4 (optional)
• Vital Signs, LOINC Code 8716-3

Real profiles will contain lots of detail about the sections, but these are omitted here in the interests of clarity.

An example of a Composition that meets these rules:

<Composition>                         
... snip ...
  <section>                       
    <code>                       
      <coding>                       
        <system value="http://loinc.org" />      
        <use value="29299-5" />          
        <value value="Reason for visit Narrative" />  
      </coding>                       
    </code>                       
    ... snip ...
  </section>
  <section>                       
    <code>                       
      <coding>                       
        <system value="http://loinc.org" />      
        <use value="46057-6" />          
        <value value="Medications section" />  
      </coding>                       
    </code>                       
    ... snip ...
    <section>                       
      <code>                       
        <coding>                       
          <system value="http://loinc.org" />      
          <use value="66149-6" />          
          <value value="Prescribed medications" />  
        </coding>                       
      </code>                       
      ... snip ...
    </section>
    <section>                       
      <code>                       
        <coding>                       
          <system value="http://loinc.org" />      
          <use value="66150-4" />          
          <value value="Over the counter medications" />  
        </coding>                       
      </code>                       
      ... snip ...
    </section>
  </section>
  <section>                       
    <code>                       
      <coding>                       
        <system value="http://loinc.org" />      
        <use value="8716-3" />          
        <value value="Vital signs" />  
      </coding>                       
    </code>                       
    ... snip ...
  </section>
</Composition>
To
do
this,
the
profile
that
implements
these
rules
needs
to
do
the
following:
On
the
base
Composition.section
element:
define
that
slicing
is
discriminated
by
code,
and
that
the
slices
are
closed
and
ordered
Then
define
3
slices
on
Composition.section:
reason-for-visit:
fixed
code,
cardinality
1..1
medication:
fixed
code,
cardinality
1..1
vital-signs:
fixed
code,
cardinality
1..1
Then,
in
the
medication
slice,
slice
the
Composition.section.section:
define
that
slicing
is
discriminated
by
code,
and
that
the
slices
are
closed
and
ordered
Then
define
2
slices
on
the
Composition.section.section
in
medication:
prescribed:
fixed
code,
cardinality
1..1
otc:
fixed
code,
cardinality
0..1
In
a
StructureDefinition,
this
will
look
like:

To do this, the profile that implements these rules needs to do the following:

• On the base Composition.section element: define that slicing is discriminated by code, and that the slices are closed and ordered
• Then define 3 slices on Composition.section:
  1. reason-for-visit: fixed code, cardinality 1..1
  2. medication: fixed code, cardinality 1..1
  3. vital-signs: fixed code, cardinality 1..1
• Then, in the medication slice, slice the Composition.section.section: define that slicing is discriminated by code, and that the slices are closed and ordered
• Then define 2 slices on the Composition.section.section in medication:
  1. prescribed: fixed code, cardinality 1..1
  2. otc: fixed code, cardinality 0..1

In a StructureDefinition, this will look like:

  <!-- setting up the slicing on Composition.section -->
  <element> 
    <path value="Composition.section"/>
    <slicing>
      <discriminator value="code"/>
      <ordered value="true"/>
      <rules value="closed"/>
    </slicing>
    <!-- net cardinality rules -->
    <min value="3"/>
    <max value="3"/>
  </element>
  
  <!-- first slice: reason for visit -->
  <element> 
    <path value="Composition.section"/>
    <name value="reason-for-visit"/> 
    <min value="1"/>
    <max value="1"/>
  </element>
  <element> 
    <path value="Composition.section.code"/>
    <min value="1"/>
    <fixedCodeableConcept>
      <coding>                       
        <system value="http://loinc.org" />      
        <use value="29299-5" />          
        <value value="Reason for visit Narrative" />  
      </coding>                       
    </fixedCodeableConcept>
  </element>
  
  <!-- second slice: medications -->
  <element> 
    <path value="Composition.section"/>
    <name value="medications"/> 
    <min value="1"/>
    <max value="1"/>
  </element>
  <element> 
    <path value="Composition.section.code"/>
    <min value="1"/>
    <fixedCodeableConcept>
      <coding>                       
        <system value="http://loinc.org" />      
        <use value="46057-6" />          
        <value value="Medications section" />  
      </coding>                       
    </fixedCodeableConcept>
  </element>

  <!-- setting up the inner slicing on medication Composition.section.section -->
  <element> 
    <path value="Composition.section.section"/>
    <slicing>
      <discriminator value="code"/>
      <ordered value="true"/>
      <rules value="closed"/>
    </slicing>
    <!-- net cardinality rules -->
    <min value="1"/>
    <max value="2"/>
  </element>

  <!-- first inner slice: prescribed medications -->
  <element> 
    <path value="Composition.section.section"/>
    <name value="prescribed"/> 
    <min value="1"/>
    <max value="1"/>
  </element>
  <element> 
    <path value="Composition.section.section.code"/>
    <min value="1"/>
    <fixedCodeableConcept>
      <coding>                       
        <system value="http://loinc.org" />      
        <use value="66149-6" />          
        <value value="Prescribed medications" />  
      </coding>                       
    </fixedCodeableConcept>
  </element>
  
  <!-- second inner slice: over the counter medications -->
  <element> 
    <path value="Composition.section.section"/>
    <name value="otc"/> 
    <min value="0"/>
    <max value="1"/>
  </element>
  <element> 
    <path value="Composition.section.section.code"/>
    <min value="1"/>
    <fixedCodeableConcept>
      <coding>                       
        <system value="http://loinc.org" />      
        <use value="66150-4" />          
        <value value="Over the counter medications" />  
      </coding>                       
    </fixedCodeableConcept>
  </element>
  
  <!-- third slice: Vital Signs -->
  <element> 
    <path value="Composition.section"/>
    <name value="vital-signs"/> 
    <min value="1"/>
    <max value="1"/>
  </element>
  <element> 
    <path value="Composition.section.code"/>
    <min value="1"/>
    <fixedCodeableConcept>
      <coding>                       
        <system value="http://loinc.org" />      
        <use value="8716-3" />          
        <value value="Vital signs" />  
      </coding>                       
    </fixedCodeableConcept>
  </element>