diff --git a/ontology/yaml/resources/HVAC/entity_types/ABSTRACT.yaml b/ontology/yaml/resources/HVAC/entity_types/ABSTRACT.yaml
index 0fa0e92e9..c9398cc64 100644
--- a/ontology/yaml/resources/HVAC/entity_types/ABSTRACT.yaml
+++ b/ontology/yaml/resources/HVAC/entity_types/ABSTRACT.yaml
@@ -6776,6 +6776,16 @@ VMADC:
   implements:
   - CONTROL
 
+MDSDC:
+  description: "Motion-dependent supply damper control."
+  is_abstract: true
+  uses:
+  - motion_status
+  - supply_air_damper_percentage_command
+  - supply_air_damper_percentage_sensor
+  implements:
+  - CONTROL
+
 OAQM:
   guid: "99e4f482-278e-40ee-9524-9f687c41ba22"
   description: "Outside air quality monitoring (particulates and gases)"
diff --git a/ontology/yaml/resources/HVAC/entity_types/VAV.yaml b/ontology/yaml/resources/HVAC/entity_types/VAV.yaml
index 2dda99ffe..0ec08a004 100644
--- a/ontology/yaml/resources/HVAC/entity_types/VAV.yaml
+++ b/ontology/yaml/resources/HVAC/entity_types/VAV.yaml
@@ -533,6 +533,13 @@ VAV_HWZTC_CHWZTC_DTM:
     - CHWZTC
     - DTM
 
+VAV_MDSDC:
+  description: "A zone VAV with ventilation control based on a motion sensor."
+  is_canonical: true
+  implements:
+    - VAV
+    - MDSDC
+
 ###################################
 ### Existing Non-standard Types ###
 ###################################