diff --git a/xyz/openbmc_project/Inventory/Decorator/Asset.interface.yaml b/xyz/openbmc_project/Inventory/Decorator/Asset.interface.yaml
index d71881e..173e770 100644
--- a/xyz/openbmc_project/Inventory/Decorator/Asset.interface.yaml
+++ b/xyz/openbmc_project/Inventory/Decorator/Asset.interface.yaml
@@ -16,8 +16,10 @@
     - name: BuildDate
       type: string
       description: >
-          The date of item manufacture in
-          YYYYMMDD format.
+          The date of item manufacture in ISO 8601 format, either as
+          YYYYMMDD or YYYYMMDDThhmmssZ.  Where 'T' is a literal character
+          to separate date fields from time and 'Z' is a literal character
+          to indicate UTC.
     - name: Model
       type: string
       description: >