diff --git a/Domains/1-Common/DistributionSystems/DistributionSystems.ecschema.xml b/Domains/1-Common/DistributionSystems/DistributionSystems.ecschema.xml
index 12884780f..819c0ca80 100644
--- a/Domains/1-Common/DistributionSystems/DistributionSystems.ecschema.xml
+++ b/Domains/1-Common/DistributionSystems/DistributionSystems.ecschema.xml
@@ -7,6 +7,7 @@
+
@@ -119,34 +120,33 @@
bis:InformationRecordElement
-
+ bis:ElementRefersToElements
-
-
- PortConnectionConnectsPorts
-
+
+
-
-
+
+
-
-
+
+ bis:ElementRefersToElements
-
-
-
-
+
+
+
+
-
diff --git a/Domains/1-Common/DistributionSystems/DistributionSystems.remarks.md b/Domains/1-Common/DistributionSystems/DistributionSystems.remarks.md
index a675b4079..9fe500c26 100644
--- a/Domains/1-Common/DistributionSystems/DistributionSystems.remarks.md
+++ b/Domains/1-Common/DistributionSystems/DistributionSystems.remarks.md
@@ -11,9 +11,11 @@ A BIS [DistributionSystem](#distributionsystem) consists of [IDistributionElemen
A given bis:PhysicalElement can implement more that one of [IDistributionFlowElement](#idistributionflowelement), [IDistributionControlElement](#idistributioncontrolelement), and [IDistributionFlowElement](#idistributionflowelement).
-Connection point information will be added in subsequent versions of the schema.
+The following class-diagrams depict the main classes and relationships in the DistributionSystems schema:
-![Class and Instance Diagrams](./media/DistributionSystems.png)
+![DistributionSystems](./media/DistributionSystems.png)
+
+![DistributionPorts](./media/DistributionPorts.png)
## Entity Classes
@@ -79,8 +81,24 @@ Equivalent to [IfcDistributionPort](https://standards.buildingsmart.org/IFC/RELE
### PortConnection
-A `PortConnection` defines a physical connection between 2 DistributionPorts. In the case where a connection is realized by some other physical element, the realizing element could be found using `PortConnectionIsRealizedByPhysicalElements` relationship.
+A `PortConnection` instance objectifies a physical connection between 2 or more DistributionPorts when needed. That is typically the case when the level of granularity being modeled includes any physical element(s) that realize a connection. In that case, the realizing element(s) could be found using the `PortConnectionIsRealizedByPhysicalElements` relationship.
+
+## Relationships
+
+### PortConnectsToPort
+
+The connection between two or more DistributionPorts can be objectified by associating a `PortConnection` instance via the `PortConnectionObjectifiesConnection` relationship. Objectifying a connection is needed when there is data (identity or business-related) to be captured about a connection, or when the level of granularity being modeled includes any physical element(s) that realize it.
+
+BIS domains extending the rules and patterns in the DistributionSystems schema are expected to subclass the `PortConnectsToPort` relationship in order to provide specific semantics and multiplicity applicable to how DistributionPort instances connect in such domain.
+
+Equivalent to [IfcRelConnectsPorts](https://standards.buildingsmart.org/IFC/RELEASE/IFC4_3/HTML/lexical/IfcRelConnectsPorts.htm).
+
+### PhysicalElementRealizesConnection
+
+When the Connection between DistributionPorts needs to be objectified, a `PortConnection` instance could be introduced, referenced by the `PortConnectsToPort` relationship via its _PortConnection_ navigation property. The `PhysicalElementRealizesConnection` relationship can then be used to associate Physical Elements with such `PortConnection` instance.
+
+Note that Physical Elements realizing a Connection are not directly enabling the flow of matter in a DistributionSystem. Thus, they are typically not `IDistributionElement`s themselves.
-A `PortConnection` generally connects two distribution ports via the `PortConnectionConnectsTwoPorts`. However, its base `PortConnectionConnectsPorts` relationship class can be used when modeling port-connections at a higher level of detail.
+Examples include bolts, rings or cement used on Connections between Pipes.
-Equivalent to [IfcRelConnectsPorts](https://standards.buildingsmart.org/IFC/RELEASE/IFC4_3/HTML/lexical/IfcRelConnectsPorts.htm).
\ No newline at end of file
+Equivalent to the _RealizingElement_ property of [IfcRelConnectsPorts](https://standards.buildingsmart.org/IFC/RELEASE/IFC4_3/HTML/lexical/IfcRelConnectsPorts.htm).
\ No newline at end of file
diff --git a/Domains/1-Common/DistributionSystems/media/DistributionPorts.png b/Domains/1-Common/DistributionSystems/media/DistributionPorts.png
new file mode 100644
index 000000000..ea794ac1f
Binary files /dev/null and b/Domains/1-Common/DistributionSystems/media/DistributionPorts.png differ
diff --git a/Domains/1-Common/DistributionSystems/media/DistributionSystems.cmap b/Domains/1-Common/DistributionSystems/media/DistributionSystems.cmap
index 2384ef459..6055a349f 100644
Binary files a/Domains/1-Common/DistributionSystems/media/DistributionSystems.cmap and b/Domains/1-Common/DistributionSystems/media/DistributionSystems.cmap differ
diff --git a/Domains/2-DisciplinePhysical/Piping/PipeworkPhysical.ecschema.xml b/Domains/2-DisciplinePhysical/Piping/PipeworkPhysical.ecschema.xml
index 32f88378d..559118bf5 100644
--- a/Domains/2-DisciplinePhysical/Piping/PipeworkPhysical.ecschema.xml
+++ b/Domains/2-DisciplinePhysical/Piping/PipeworkPhysical.ecschema.xml
@@ -155,12 +155,12 @@
-
- dsys:PortConnectionConnectsTwoPorts
+
+ dsys:PortConnectsToPorts
-
+
-
+