diff --git a/subprojects/nemora-postd/event_message.proto b/subprojects/nemora-postd/event_message.proto
new file mode 100644
index 0000000..0b3f9eb
--- /dev/null
+++ b/subprojects/nemora-postd/event_message.proto
@@ -0,0 +1,42 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+syntax = "proto2";
+
+// Note: it is important that the application is resilient to 
+// incorrectly encoded protobuf's.
+
+message EventSeries {
+  enum PostCodeProtocol {
+    PROTOCOL_UNSPECIFIED = 0;
+    EIGHT_BIT_WITH_EXTENDED_CODES = 1;
+    NATIVE_32_BIT = 2;
+  }
+  // A fixed integer to confirm the type of this protobuf: 0x890ebd38ec325800
+  optional fixed64 magic = 1;
+  // Firmware version of the device reporting this data.
+  optional int32 fw_version = 2;
+  // Primary MAC address of the server this data is from (in network order).
+  optional bytes mac = 3;
+  // Time message was sent in microseconds.
+  optional int64 sent_time_us = 4;
+  // Zero or more POST codes. Some codes may be missed because the host can
+  // send out codes faster than the EC handles them. While standard values are
+  // only 8-bits, non-standard values above 255 may be used.
+  repeated int32 postcodes = 5;
+  reserved 6 to 13;
+  optional PostCodeProtocol postcodes_protocol = 14;
+}
+
+package platforms.nemora.proto;