diff --git a/config-linux.md b/config-linux.md
index 5e77c113a..90e2cbbf8 100644
--- a/config-linux.md
+++ b/config-linux.md
@@ -34,7 +34,7 @@ The following parameters can be specified to setup namespaces:
     * **`uts`** the container will be able to have its own hostname and domain name
     * **`user`** the container will be able to remap user and group IDs from the host to local users and groups within the container
 
-* **`path`** *(string, optional)* - path to namespace file
+* **`path`** *(string, optional)* - path to namespace file in the [runtime mount namespace](glossary.md#runtime-namespace)
 
 If a path is specified, that particular file is used to join that type of namespace.
 Also, when a path is specified, a runtime MUST assume that the setup for that particular namespace has already been done and error out if the config specifies anything else related to that namespace.
diff --git a/glossary.md b/glossary.md
index f9d11c4f5..6b6eb5949 100644
--- a/glossary.md
+++ b/glossary.md
@@ -13,6 +13,10 @@ The [`config.json`](config.md) file in a [bundle](#bundle) which defines the int
 An environment for executing processes with configurable isolation and resource limitations.
 For example, namespaces, resource limits, and mounts are all part of the container environment.
 
+## Container namespace
+
+On Linux, a leaf in the [namespace][namespaces.7] hierarchy in which the [configured process](config.md#process-configuration) executes.
+
 ## JSON
 
 All configuration [JSON][] MUST be encoded in [UTF-8][].
@@ -22,5 +26,11 @@ All configuration [JSON][] MUST be encoded in [UTF-8][].
 An implementation of this specification.
 It reads the [configuration files](#configuration) from a [bundle](#bundle), uses that information to create a [container](#container), launches a process inside the container, and performs other [lifecycle actions](runtime.md).
 
+## Runtime namespace
+
+On Linux, a leaf in the [namespace][namespaces.7] hierarchy from which the [runtime](#runtime) process is executed.
+New container namespaces will be created as children of the runtime namespaces.
+
 [JSON]: http://json.org/
 [UTF-8]: http://www.unicode.org/versions/Unicode8.0.0/ch03.pdf
+[namespaces.7]: http://man7.org/linux/man-pages/man7/namespaces.7.html