diff --git a/README.md b/README.md
index ae90f20..bf500df 100644
--- a/README.md
+++ b/README.md
@@ -1,13 +1,5 @@
 [![Readium Logo](https://readium.org/assets/logos/readium-logo.png)](https://readium.org)
 
-<style>
-.rfc {
-    color: #d55;
-    font-variant: small-caps;
-    font-style: normal;
-}
-</style>
-
 # Readium Web Publication Manifest
 
 The Readium Web Publication Manifest is a JSON-based document meant to represent and distribute publications over HTTPS.
@@ -363,3 +355,11 @@ In addition to the EPUB format, a Readium Web Publication <span class="rfc">may<
 A JSON Schema is available under version control at [https://github.com/readium/webpub-manifest/tree/master/schema](https://github.com/readium/webpub-manifest/tree/master/schema)
 
 For the purpose of validating a Readium Web Publication Manifest, use the following JSON Schema resource: [https://readium.org/webpub-manifest/schema/publication.schema.json](https://readium.org/webpub-manifest/schema/publication.schema.json)
+
+<style>
+.rfc {
+    color: #d55;
+    font-variant: small-caps;
+    font-style: normal;
+}
+</style>
diff --git a/contexts/default/README.md b/contexts/default/README.md
index 2bc9f08..b8f9d6a 100644
--- a/contexts/default/README.md
+++ b/contexts/default/README.md
@@ -1,11 +1,3 @@
-<style>
-.rfc {
-    color: #d55;
-    font-variant: small-caps;
-    font-style: normal;
-}
-</style>
-
 # Default Context
 
 The Readium Web Publication Manifest defines a shared external context document hosted by the Readium Foundation and based primarily on schema.org and its extensions.
@@ -398,4 +390,12 @@ If we use another example with more complex metadata expression and an extension
 
 In order to convert EPUB packages into a Readium Web Publication Manifest, we've documented how each metadata item listed in the default context is mapped to an equivalent in EPUB 2.x or 3.x.
 
-This live document is available at: [https://readium.org/architecture/streamer/parser/metadata](https://readium.org/architecture/streamer/parser/metadata)
\ No newline at end of file
+This live document is available at: [https://readium.org/architecture/streamer/parser/metadata](https://readium.org/architecture/streamer/parser/metadata)
+
+<style>
+.rfc {
+    color: #d55;
+    font-variant: small-caps;
+    font-style: normal;
+}
+</style>
\ No newline at end of file
diff --git a/extensions/audiobook.md b/extensions/audiobook.md
index 8f88723..3606361 100644
--- a/extensions/audiobook.md
+++ b/extensions/audiobook.md
@@ -1,13 +1,5 @@
 [![Readium Logo](https://readium.org/assets/logos/readium-logo.png)](https://readium.org)
 
-<style>
-.rfc {
-    color: #d55;
-    font-variant: small-caps;
-    font-style: normal;
-}
-</style>
-
 # Audiobook Profile
 
 ## Example
@@ -97,7 +89,7 @@ In addition, all Link Objects <span class="rfc">should</span> also include the `
 
 In order to support multiple variants of the same audiobook (using a different format or bitrate for instance), Link Objects in the `readingOrder` <span class="rfc">may</span> rely on the `alternate` key:
 
-```
+```json
 {
   "href": "http://example.org/part1.mp3", 
   "type": "audio/mpeg", 
@@ -139,3 +131,11 @@ Over 10,000+ audiobooks are also available in this format through [the Internet
 ## Demo
 
 [A demo of the Flatland example is also available](https://player.cantookaudio.com/aHR0cHM6Ly9yZWFkaXVtLm9yZy93ZWJwdWItbWFuaWZlc3QvZXhhbXBsZXMvRmxhdGxhbmQvbWFuaWZlc3QuanNvbg==) through a Web App developed by [De Marque](https://www.demarque.com/). 
+
+<style>
+.rfc {
+    color: #d55;
+    font-variant: small-caps;
+    font-style: normal;
+}
+</style>
diff --git a/schema/metadata.schema.json b/schema/metadata.schema.json
index f711666..3217045 100644
--- a/schema/metadata.schema.json
+++ b/schema/metadata.schema.json
@@ -117,6 +117,9 @@
     "imprint": {
       "$ref": "contributor.schema.json"
     },
+    "subject": {
+      "$ref": "subject.schema.json"
+    },
     "readingProgression": {
       "type": "string",
       "enum": [
diff --git a/schema/subject-object.schema.json b/schema/subject-object.schema.json
new file mode 100644
index 0000000..c71bc3b
--- /dev/null
+++ b/schema/subject-object.schema.json
@@ -0,0 +1,45 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "$id": "https://readium.org/webpub-manifest/schema/subject-object.schema.json",
+  "title": "Subject Object",
+  "type": "object",
+  "properties": {
+    "name": {
+      "anyOf": [
+        {
+          "type": "string"
+        },
+        {
+          "description": "The language in a language map must be a valid BCP 47 tag.",
+          "type": "object",
+          "patternProperties": {
+            "^((?<grandfathered>(en-GB-oed|i-ami|i-bnn|i-default|i-enochian|i-hak|i-klingon|i-lux|i-mingo|i-navajo|i-pwn|i-tao|i-tay|i-tsu|sgn-BE-FR|sgn-BE-NL|sgn-CH-DE)|(art-lojban|cel-gaulish|no-bok|no-nyn|zh-guoyu|zh-hakka|zh-min|zh-min-nan|zh-xiang))|((?<language>([A-Za-z]{2,3}(-(?<extlang>[A-Za-z]{3}(-[A-Za-z]{3}){0,2}))?)|[A-Za-z]{4}|[A-Za-z]{5,8})(-(?<script>[A-Za-z]{4}))?(-(?<region>[A-Za-z]{2}|[0-9]{3}))?(-(?<variant>[A-Za-z0-9]{5,8}|[0-9][A-Za-z0-9]{3}))*(-(?<extension>[0-9A-WY-Za-wy-z](-[A-Za-z0-9]{2,8})+))*(-(?<privateUse>x(-[A-Za-z0-9]{1,8})+))?)|(?<privateUse2>x(-[A-Za-z0-9]{1,8})+))$": {
+              "type": "string"
+            }
+          },
+          "additionalProperties": false,
+          "minProperties": 1
+        }
+      ]
+    },
+    "sortAs": {
+      "type": "string"
+    },
+    "code": {
+      "type": "string"
+    },
+    "scheme": {
+      "type": "string",
+      "format": "uri"
+    },
+    "links": {
+      "type": "array",
+      "items": {
+        "$ref": "link.schema.json"
+      }
+    }
+  },
+  "required": [
+    "name"
+  ]
+}
diff --git a/schema/subject.schema.json b/schema/subject.schema.json
new file mode 100644
index 0000000..c4cd4cd
--- /dev/null
+++ b/schema/subject.schema.json
@@ -0,0 +1,28 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "$id": "https://readium.org/webpub-manifest/schema/subject.schema.json",
+  "title": "Subject",
+  "anyOf": [
+    {
+      "type": "string"
+    },
+    {
+      "type": "array",
+      "items": {
+        "anyOf": [
+          {
+            "type": "string"
+          },
+          {
+            "type": "object",
+            "$ref": "subject-object.schema.json"
+          }
+        ]
+      }
+    },
+    {
+      "type": "object",
+      "$ref": "subject-object.schema.json"
+    }
+  ]
+}