diff --git a/specification/storage/data-plane/Azure.Storage.Files.DataLake/stable/2026-02-06/DataLakeStorage.json b/specification/storage/data-plane/Azure.Storage.Files.DataLake/stable/2026-02-06/DataLakeStorage.json
index 2ba8e91b21d2..e66db102314c 100644
--- a/specification/storage/data-plane/Azure.Storage.Files.DataLake/stable/2026-02-06/DataLakeStorage.json
+++ b/specification/storage/data-plane/Azure.Storage.Files.DataLake/stable/2026-02-06/DataLakeStorage.json
@@ -632,6 +632,9 @@
           {
             "$ref": "#/parameters/Continuation"
           },
+          {
+            "$ref": "#/parameters/BlobType"
+          },
           {
             "name": "mode",
             "in": "query",
@@ -2584,6 +2587,120 @@
           ]
         }
       ]
+    },
+    "/{filesystem}/{path}?comp=concurrentAppend": {
+      "patch": {
+        "tags": [
+          "blob"
+        ],
+        "consumes": [
+          "application/octet-stream"
+        ],
+        "operationId": "Path_ConcurrentAppend",
+        "description": "Appends data to the file",
+        "parameters": [
+          {
+            "$ref": "#/parameters/Timeout"
+          },
+          {
+            "$ref": "#/parameters/ApiVersionParameter"
+          },
+          {
+            "$ref": "#/parameters/ClientRequestId"
+          },
+          {
+            "$ref": "#/parameters/AppendMode"
+          },
+          {
+            "$ref": "#/parameters/Body"
+          },
+          {
+            "$ref": "#/parameters/ContentLength"
+          },
+          {
+            "$ref": "#/parameters/TransactionalContentMD5"
+          },
+          {
+            "$ref": "#/parameters/FastPathSessionData"
+          },
+          {
+            "$ref": "#/parameters/ConditionAppendPos"
+          }
+        ],
+        "responses": {
+          "202": {
+            "description": "Data was appended to the file",
+            "headers": {
+              "Date": {
+                "type": "string",
+                "format": "date-time-rfc1123",
+                "description": "A UTC date/time value generated by the service that indicates the time at which the response was initiated."
+              },
+              "x-ms-request-id": {
+                "x-ms-client-name": "RequestId",
+                "type": "string",
+                "description": "A server-generated UUID recorded in the analytics logs for troubleshooting and correlation."
+              },
+              "x-ms-client-request-id": {
+                "x-ms-client-name": "ClientRequestId",
+                "type": "string",
+                "description": "If a client request id header is sent in the request, this header will be present in the response with the same value."
+              },
+              "x-ms-version": {
+                "x-ms-client-name": "Version",
+                "type": "string",
+                "description": "The version of the REST protocol used to process the request."
+              },
+              "x-ms-committed-block-count": {
+                "x-ms-client-name": "CommittedBlockCount",
+                "type": "integer",
+                "format": "int64",
+                "description": "The number of blocks that have been committed to this blob."
+              },
+              "x-ms-fastpath-session-data": {
+                "x-ms-client-name": "FastPathSessionData",
+                "type": "string",
+                "description": "Fast Path session data."
+              },
+              "x-ms-fastpath-session-expiry-time": {
+                "x-ms-client-name": "FastPathSessionDataExpiry",
+                "type": "string",
+                "format": "date-time-rfc1123",
+                "description": "A UTC date/time value generated by the service that indicates the time at which the Fast Path data will expire."
+              }
+            }
+          },
+          "default": {
+            "description": "Failure",
+            "headers": {
+              "x-ms-error-code": {
+                "x-ms-client-name": "ErrorCode",
+                "type": "string"
+              }
+            },
+            "schema": {
+              "$ref": "#/definitions/StorageError"
+            }
+          }
+        }
+      },
+      "parameters": [
+        {
+          "$ref": "#/parameters/FileSystem"
+        },
+        {
+          "$ref": "#/parameters/Path"
+        },
+        {
+          "name": "action",
+          "in": "query",
+          "required": true,
+          "type": "string",
+          "enum": [
+            "concurrentAppend"
+          ]
+        }
+      ]
     }
   },
   "parameters": {
@@ -3337,6 +3454,58 @@
       "x-ms-parameter-location": "method",
       "description": "Specifies the encryption context to set on the file."
     },
+    "AppendMode": {
+      "name": "appendmode",
+      "x-ms-client-name": "AppendMode",
+      "in": "query",
+      "required": false,
+      "type": "string",
+      "enum": [
+        "none",
+        "autoCreate"
+      ],
+      "x-ms-enum": {
+        "name": "AppendMode",
+        "modelAsString": false
+      },
+      "x-ms-parameter-location": "method",
+      "description": "Optional.  Indicates concurrent append mode"
+    },
+    "BlobType": {
+      "name": "blobtype",
+      "x-ms-client-name": "BlobType",
+      "in": "query",
+      "required": false,
+      "type": "string",
+      "enum": [
+        "none",
+        "appendblob"
+      ],
+      "x-ms-enum": {
+        "name": "BlobType",
+        "modelAsString": false
+      },
+      "x-ms-parameter-location": "method",
+      "description": "Optional.  Indicates concurrent append mode"
+    },
+    "FastPathSessionData": {
+      "name": "x-ms-fastpath-session-data",
+      "x-ms-client-name": "fastPathSessionData",
+      "in": "header",
+      "required": false,
+      "type": "string",
+      "x-ms-parameter-location": "method"
+    },
+    "ConditionAppendPos": {
+      "name": "x-ms-conditional-appendpos",
+      "x-ms-client-name": "conditionalAppendPosition",
+      "in": "header",
+      "required": false,
+      "type": "integer",
+      "format": "int64",
+      "x-ms-parameter-location": "method",
+      "description": "Optional conditional header, used only for the Append Block operation. A number indicating the byte offset to compare. Append Block will succeed only if the append position is equal to this number. If it is not, the request will fail with the AppendPositionConditionNotMet error (HTTP status code 412 - Precondition Failed)."
+    },
     "Paginated": {
       "name": "paginated",
       "in": "query",