diff --git a/api/swagger.yaml b/api/swagger.yaml
index c0b442416d..3c0c272e5c 100644
--- a/api/swagger.yaml
+++ b/api/swagger.yaml
@@ -2449,7 +2449,15 @@ definitions:
     properties:
       PluginSpec:
         type: "object"
-        description: "Invalid when specified with `ContainerSpec`. *(Experimental release only.)*"
+        description: |
+          Plugin spec for the service.  *(Experimental release only.)*
+
+          <p><br /></p>
+
+          > **Note**: ContainerSpec, NetworkAttachmentSpec, and PluginSpec are
+          > mutually exclusive. PluginSpec is only used when the Runtime field
+          > is set to `plugin`. NetworkAttachmentSpec is used when the Runtime
+          > field is set to `attachment`.
         properties:
           Name:
             description: "The name or 'alias' to use for the plugin."
@@ -2476,7 +2484,15 @@ definitions:
                     type: "string"
       ContainerSpec:
         type: "object"
-        description: "Invalid when specified with `PluginSpec`."
+        description: |
+          Container spec for the service.
+
+          <p><br /></p>
+
+          > **Note**: ContainerSpec, NetworkAttachmentSpec, and PluginSpec are
+          > mutually exclusive. PluginSpec is only used when the Runtime field
+          > is set to `plugin`. NetworkAttachmentSpec is used when the Runtime
+          > field is set to `attachment`.
         properties:
           Image:
             description: "The image name to use for the container"
@@ -2689,7 +2705,16 @@ definitions:
               - "process"
               - "hyperv"
       NetworkAttachmentSpec:
-        description: "Read-only spec type for non-swarm containers attached to swarm overlay networks"
+        description: |
+          Read-only spec type for non-swarm containers attached to swarm overlay
+          networks.
+
+          <p><br /></p>
+
+          > **Note**: ContainerSpec, NetworkAttachmentSpec, and PluginSpec are
+          > mutually exclusive. PluginSpec is only used when the Runtime field
+          > is set to `plugin`. NetworkAttachmentSpec is used when the Runtime
+          > field is set to `attachment`.
         type: "object"
         properties:
           ContainerID:
diff --git a/docs/api/version-history.md b/docs/api/version-history.md
index 61245e14a7..8c56a1c19f 100644
--- a/docs/api/version-history.md
+++ b/docs/api/version-history.md
@@ -13,6 +13,12 @@ keywords: "API, Docker, rcli, REST, documentation"
      will be rejected.
 -->
 
+## V1.38 API changes
+
+* `GET /tasks` and `GET /tasks/{id}` now return a `NetworkAttachmentSpec` field,
+  containing the `ContainerID` for non-service containers connected to "attachable"
+  swarm-scoped networks.
+
 ## v1.37 API changes
 
 [Docker Engine API v1.37](https://docs.docker.com/engine/api/v1.37/) documentation