Add presentation section.

permission-element.bs

@@ -583,8 +583,6 @@ To <dfn for="HTMLPermissionElement">recheck type permissibility</dfn> for a
 
 # Rendering the <{permission}> Element # {#rendering}
 
-## Presentation ## {#presentation}
-
 The <{permission}> element is a [=non-devolvable widget=] and is chiefly
 rendered like a <{button}>. The button label is largely expected to be
 determined by the browser, rather than the page, and reflects the
@@ -595,6 +593,47 @@ constraints to prevent abuse (e.g. minimum and maximum sizes for fonts and
 the label itself). The page can also select a locale for the text via the
 <{html-global/lang}> attribute.
 
+## Presentation ## {#presentation}
+
+ISSUE: There isn't much precedence for describing the user agent UI in detail.
+    It may be better to leave more freedom to user agents.
+
+The <{permission}> element contains browser-chosen content, text and maybe an
+icon. Activating it will [=prompt the user to choose=].
+This provides two bits of user interface that a user can interact with.
+The [=user agent=] is largely free to determine these &mdash; rendering of the
+<{permission}> element and the subsequent [=prompt the user to choose|permission
+prompt=] &mdash; in whichever way it thinks best convey's the element's intent.
+
+
+UI options for the <{permission}> element's presentation include:
+
+* Name the [=powerful features=] listed in {{[[Types]]}}, in the language
+    indicated by the [=language=] of the element. Note that this would
+    always be the language indicated by the <{html-global/lang}> attribute,
+    if present.
+* An icon indicating the [=powerful feature=] type or types.
+* The current [=permission state=] of the [=powerful feature=] in questions.
+    For example, if the [=powerful feature|permission=] is already
+    {{PermissionState/granted}}, the <{permission}> element might be labeled
+    as "geolocation already in use".
+* A modal [=prompt the user to choose|prompt=] with a "scrim".
+    (I.e., darkening out the page behind the prompt.)
+    This would normally quite disruptive. But here our goal is to ensure a
+    user means to make this choice.
+
+[=User agents=] are encouraged to name or describe the [=powerful features=]
+in a way that's consistent with similar usage in program or the platform it
+is running on.
+
+Very non-normative examples might be:
+
+* `<permission lang="de" types="geolocation">`: "Standort verwenden".
+* `<permission types="microphone">` (in an English language page): "Use microphone. &#x1f3a4;".
+* Upon activiating `<permission types="microphone">`, when the corresponding
+    [=permission state=] is {{PermissionState/denied}}, modify the text to
+    "Continue blocking".
+
 ## Styling ## {#style}
 
 A <{permission}> element constrains the styling that can be applied to it.