diff --git a/index.bs b/index.bs
index fe7ec25..3d54489 100644
--- a/index.bs
+++ b/index.bs
@@ -34,6 +34,7 @@ urlPrefix: https://tools.ietf.org/html/draft-ietf-httpbis-header-structure; spec
             text: list; url: #section-3.1
     type: abstract-op
         text: serialize Structured Header; url: #section-4.1
+    spec:infra; type:dfn; for:/; text:list
 </pre>
 <pre class="biblio">
 {
@@ -316,23 +317,27 @@ Interface {#interface}
 =================
 
 <pre class="idl">
-dictionary NavigatorUABrandVersionDict {
-  required DOMString brand;
+dictionary NavigatorUABrandVersion {
+  DOMString brand;
   DOMString version;
 };
 
+dictionary UADataValues {
+  DOMString platform; 
+  DOMString platformVersion;
+  DOMString architecture;
+  DOMString model;
+};
+
 [Exposed=Window]
 interface NavigatorUAData {
-  readonly attribute FrozenArray&lt;NavigatorUABrandVersionDict&gt; brand;
+  readonly attribute FrozenArray&lt;NavigatorUABrandVersion&gt; uaList;
   readonly attribute boolean mobile;
-  Promise&lt;DOMString&gt; getPlatform();
-  Promise&lt;SOMString&gt; getPlatformVersion();
-  Promise&lt;DOMString&gt; getArchitecture();
-  Promise&lt;DOMString&gt; getModel();
+  Promise&lt;UADataValues&gt; getHighEntropyValues(sequence&lt;DOMString&gt; hints);
 };
 
 interface mixin NavigatorUA {
-  [SecureContext] NavigatorUAData getUserAgent();
+  [SecureContext] readonly attribute NavigatorUAData userAgentData;
 };
 Navigator includes NavigatorUA;
 
@@ -340,32 +345,68 @@ Navigator includes NavigatorUA;
 
 Processing model {#processing}
 --------------
-<dfn method for="NavigatorUA"><code>getUserAgent()</code></dfn> method MUST run these steps:
+
+<h3 id="monkeypatch-html-windoworworkerglobalscope"><code>WindowOrWorkerGlobalScope</code></h3>
+
+Each [=user agent=] has an associated <dfn>UA list</dfn>, which is a [=/list=] created by running [=create UA list=].
+
+Every {{WindowOrWorkerGlobalScope}} object has an associated <dfn for="WindowOrWorkerGlobalScope">UA frozen array</dfn>, which is a <code><a interface>FrozenArray</a>&lt;<a dictionary>NavigatorUABrandVersion</a>></code>. It is initially the result of [=create a frozen array|creating a frozen array=] from the [=user agent=]'s [=UA list=].
+
+<h3 id="create-ua-list-section">Create a UA list</h3>
+
+When asked to run the <dfn>create UA list</dfn> algorithm, the user agent MUST run the following steps:
+1. Let |list| be a [=/list=].
+
+2. Collect pairs of [=user agent/brand=] and [=user agent/significant version=] which represent the user agent,
+    its equivalence class and/or its rendering engine.
+
+3. For each pair:
+
+    1. Let |dict| be a new {{NavigatorUABrandVersion}} dictionary,
+        with [=user agent/brand=] as {{NavigatorUABrandVersion/brand}} and [=user agent/significant version=] as {{NavigatorUABrandVersion/version}}. 
+
+    2. Append |dict| to |list|.
+
+4.  The user agent MAY execute the following steps:
+
+    1.  [=list/Append=] additional items to |list| containing {{NavigatorUABrandVersion}} objects,
+        initialized with arbitrary {{NavigatorUABrandVersion/brand}} and {{NavigatorUABrandVersion/version}} combinations.
+
+    2.  Randomize the order of the items in |list|.
+
+    Note: See [[#grease]] for more details on why these steps might be appropriate.
+
+5. Return |list|.
+
+<h3 id="getters">Getters</h3>
+
+On getting, the {{NavigatorUAData/uaList}} attribute MUST return [=this=]'s [=relevant global object=]'s [=WindowOrWorkerGlobalScope/UA frozen array=].
+
+On getting, the {{NavigatorUAData/mobile}} attribute must return the user agent's [=user agent/mobileness=].
+
+<h3 id="getHighEntropyValues"><code>getHighEntropyValues</code> method</h3>
+
+The <dfn method for="NavigatorUA"><code>getHighEntropyValues(|hints|)</code></dfn> method MUST run these steps:
 
 1. Let |p| be a [=a new promise=].
 
 2.  Run the following steps [=in parallel=]:
 
-    1.  Let |UAData| be a new {{NavigatorUAData}} object whose values are initialized as follows:
+    1. Let |uaData| be a new {{UADataValues}}.
 
-        :   {{NavigatorUAData/brand}}
-        ::  The user agent's [=user agent/brand=].
-        :   {{NavigatorUAData/getPlatform}}
-        ::  The user agent's [=user agent/platform brand=].
-        :   {{NavigatorUAData/getPlatformVersion}}
-        ::  The user agent's [=user agent/platform version=].
-        :   {{NavigatorUAData/getArchitecture}}
-        ::  The user agent's [=user agent/platform architecture=].
-        :   {{NavigatorUAData/getModel}}
-        ::  The user agent's [=user agent/model=].
-        :   {{NavigatorUAData/mobile}}
-        ::  The user agent's [=user agent/mobileness=].
+    2. If |hints| [=contains=] "platform", set |uaData|["{{UADataValues/platform}}"] to the user agent's [=user agent/platform brand=].
 
-    2.  [=Resolve=] |p| with |UAData|.
+    3. If |hints| [=contains=] "platformVersion", set |uaData|["{{UADataValues/platformVersion}}"] to the user agent's [=user agent/platform version=].
 
-3.  Return |p|.
+    4. If |hints| [=contains=] "architecture", set |uaData|["{{UADataValues/architecture}}"] to the user agent's [=user agent/platform architecture=].
+
+    5. If |hints| [=contains=] "model", set |uaData|["{{UADataValues/model}}"] to the user agent's [=user agent/model=].
+
+    6. [=Queue a task=] to [=resolve=] |p| with |uaData|.
 
-ISSUE: Provide a method to only access the UA's significant version.
+ISSUE: Add a specific task source this is queued on.
+
+3.  Return |p|.
 
 Security and Privacy Considerations {#security-privacy}
 ===================================
@@ -590,4 +631,3 @@ Author/Change controller:
 
 Specification document:
 : this specification ([[#user-agent]]), and Section 5.5.3 of [[RFC7231]]
-