Multiple attributes in the same category in XACML 3.0

I'm learning XACML 3.0 and want to ask, if I have two attributes with different ID But in the same category i.e (Category="urn:oasis:names:tc:xacml:3.0:attribute-category:resource"), this interpretation as two different attributes for the same category or as two separate request with a single attribute.

Thank you .

If you create a XACML request with 4 different categories (e.g. Subject, Action, Resource, and Environment) and you add one or more attributes per category, then you will always obtain a single request and therefore a single response.

Example:

<xacml-ctx:Request ReturnPolicyIdList="true" CombinedDecision="false" xmlns:xacml-ctx="urn:oasis:names:tc:xacml:3.0:core:schema:wd-17">
   <xacml-ctx:Attributes Category="urn:oasis:names:tc:xacml:3.0:attribute-category:action" >
      <xacml-ctx:Attribute AttributeId="action-id" IncludeInResult="true">
         <xacml-ctx:AttributeValue DataType="http://www.w3.org/2001/XMLSchema#string">view</xacml-ctx:AttributeValue>
      </xacml-ctx:Attribute>
   </xacml-ctx:Attributes>
   <xacml-ctx:Attributes Category="urn:oasis:names:tc:xacml:3.0:attribute-category:environment" >
   </xacml-ctx:Attributes>
   <xacml-ctx:Attributes Category="urn:oasis:names:tc:xacml:3.0:attribute-category:resource" >
      <xacml-ctx:Attribute AttributeId="resource-type" IncludeInResult="true">
         <xacml-ctx:AttributeValue DataType="http://www.w3.org/2001/XMLSchema#string">medical record</xacml-ctx:AttributeValue>
      </xacml-ctx:Attribute>
      <xacml-ctx:Attribute AttributeId="resource-id" IncludeInResult="true">
         <xacml-ctx:AttributeValue DataType="http://www.w3.org/2001/XMLSchema#string">doc#123</xacml-ctx:AttributeValue>
      </xacml-ctx:Attribute>
   </xacml-ctx:Attributes>
   <xacml-ctx:Attributes Category="urn:oasis:names:tc:xacml:1.0:subject-category:access-subject" >
      <xacml-ctx:Attribute AttributeId="user.role" IncludeInResult="true">
         <xacml-ctx:AttributeValue DataType="http://www.w3.org/2001/XMLSchema#string">manager</xacml-ctx:AttributeValue>
      </xacml-ctx:Attribute>
      <xacml-ctx:Attribute AttributeId="user.identifier" IncludeInResult="true">
         <xacml-ctx:AttributeValue DataType="http://www.w3.org/2001/XMLSchema#string">Alice</xacml-ctx:AttributeValue>
      </xacml-ctx:Attribute>
   </xacml-ctx:Attributes>
</xacml-ctx:Request>

The aforementioned XACML request means

Can Alice the manager view medical record doc#123?

If you create a XACML request where you repeat a category several times, then you are building a Multiple Decision Request. For instance we could ask

Can Alice the manager view and edit medical record doc#123?

In XACML this would become:

<xacml-ctx:Request ReturnPolicyIdList="true" CombinedDecision="false" xmlns:xacml-ctx="urn:oasis:names:tc:xacml:3.0:core:schema:wd-17">
   <xacml-ctx:Attributes Category="urn:oasis:names:tc:xacml:3.0:attribute-category:action" >
      <xacml-ctx:Attribute AttributeId="action-id" IncludeInResult="true">
         <xacml-ctx:AttributeValue DataType="http://www.w3.org/2001/XMLSchema#string">view</xacml-ctx:AttributeValue>
      </xacml-ctx:Attribute>
   </xacml-ctx:Attributes>
   <xacml-ctx:Attributes Category="urn:oasis:names:tc:xacml:3.0:attribute-category:resource" >
      <xacml-ctx:Attribute AttributeId="resource-type" IncludeInResult="true">
         <xacml-ctx:AttributeValue DataType="http://www.w3.org/2001/XMLSchema#string">medical record</xacml-ctx:AttributeValue>
      </xacml-ctx:Attribute>
      <xacml-ctx:Attribute AttributeId="resource-id" IncludeInResult="true">
         <xacml-ctx:AttributeValue DataType="http://www.w3.org/2001/XMLSchema#string">doc#123</xacml-ctx:AttributeValue>
      </xacml-ctx:Attribute>
   </xacml-ctx:Attributes>
   <xacml-ctx:Attributes Category="urn:oasis:names:tc:xacml:1.0:subject-category:access-subject" >
      <xacml-ctx:Attribute AttributeId="user.role" IncludeInResult="true">
         <xacml-ctx:AttributeValue DataType="http://www.w3.org/2001/XMLSchema#string">manager</xacml-ctx:AttributeValue>
      </xacml-ctx:Attribute>
      <xacml-ctx:Attribute AttributeId="user.identifier" IncludeInResult="true">
         <xacml-ctx:AttributeValue DataType="http://www.w3.org/2001/XMLSchema#string">Alice</xacml-ctx:AttributeValue>
      </xacml-ctx:Attribute>
   </xacml-ctx:Attributes>
   <xacml-ctx:Attributes Category="urn:oasis:names:tc:xacml:3.0:attribute-category:action" >
      <xacml-ctx:Attribute AttributeId="action-id" IncludeInResult="true">
         <xacml-ctx:AttributeValue DataType="http://www.w3.org/2001/XMLSchema#string">edit</xacml-ctx:AttributeValue>
      </xacml-ctx:Attribute>
   </xacml-ctx:Attributes>
   <xacml-ctx:Attributes Category="urn:oasis:names:tc:xacml:3.0:attribute-category:environment" >
   </xacml-ctx:Attributes>
</xacml-ctx:Request>

Note that the order of the categories do not matter. You can also give your categories XML identifiers and create a XACML multiple decision request by reference but this is not as commonly used.

You will find an interesting article on the topic and on the Axiomatics SDK here.