diff --git a/configs/dependency-specs/README.md b/configs/dependency-specs/README.md
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+This directory contains YAML files which are used to define how to query the
+latest available versions of dependencies for a particular toolchain config.
+
+A single dependency specification file indicates the location of the Bazel
+image used to determine the latest Bazel version and the toolchain container
+used to determine the latest toolchain container version.
+
+The following is an example YAML config for the RBE Ubuntu 16.04 container.
+```yaml
+# Location of the config-dependency tracker file on the repository
+# specified in the Github spec YAML file to the toolchain configs update
+# service.
+revisionsFilePath: "configs/dependency-tracking/ubuntu16_04.yaml" 
+gcrDeps:
+  # The RBE Ubuntu 16.04 toolchain container.
+  - name: "IMAGE"
+    location: "l.gcr.io/google/rbe-ubuntu16-04"
+    tag: "latest"
+  # The Bazel container.
+  - name: "BAZEL"
+    location: "l.gcr.io/google/bazel"
+    tag: "latest"
+```
+
diff --git a/configs/dependency-specs/ubuntu16_04.yaml b/configs/dependency-specs/ubuntu16_04.yaml
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+# Location of the config-dependency tracker file on the repository
+# specified in the Github spec YAML file to the toolchain configs update
+# service.
+revisionsFilePath: "configs/dependency-tracking/ubuntu16_04.yaml"
+gcrDeps:
+  # The RBE Ubuntu 16.04 toolchain container.
+  - name: "IMAGE"
+    location: "l.gcr.io/google/rbe-ubuntu16-04"
+    tag: "latest"
+  # The Bazel container.
+  - name: "BAZEL"
+    location: "l.gcr.io/google/bazel"
+    tag: "latest"
+
+