clarify charter scope

Addressing patcg#3, clarify that features may include both client and server implementation, but are client-facing in some way.

charter.html

@@ -101,17 +101,9 @@ <h2 id=mission>Mission</h2>
 publishers, ad buyers, advertising platforms and intermediaries, privacy
 advocates, web application developers, and other interested parties.
 
-
 <h2 id=scope>Scope</h2>
 
-<p>The Community Group will incubate new web platform features intended to be
-implemented in browsers or similar user agents.  The purpose of these features
-is to support web advertising and provide users with privacy guarantees with a
-strong technical basis.
-
-<p>The Community Group may consider designs that allow user agents for the same
-user &mdash; including non-browser agents, like Operating Systems &mdash; to
-collaborate in providing advertising features.
+<p>The Community Group will incubate new web platform features to support web advertising and provide users with privacy with a strong technical basis. Features may be designed for implementation by user agents — including non-browser agents like operating systems or mobile apps that use web technologies — and by servers providing client-facing functionality.</p>
 
 <p>The Community Group will develop and document a set of common
 principles by which proposed private advertising features can
@@ -124,12 +116,9 @@ <h2 id=scope>Scope</h2>
 working group shall provide a venue for formal standardization of work that this
 Community Group incubates.
 
-
 <h3 id=out-of-scope>Out of Scope</h3>
-
-<p>Features that support advertising but provide privacy by means that are
-primarily non-technical should be proposed elsewhere.
-
+
+<p>Features that support advertising but provide privacy by means that are primarily non-technical and features that are server-to-server without a user-facing component should be proposed elsewhere.</p>
 
 <h2 id=work>Work</h2>