diff --git a/xml/System.Net.Http/HttpClient.xml b/xml/System.Net.Http/HttpClient.xml
index 1489a4c9230..9820a116965 100644
--- a/xml/System.Net.Http/HttpClient.xml
+++ b/xml/System.Net.Http/HttpClient.xml
@@ -362,7 +362,15 @@ The environment variables used for `DefaultProxy` initialization on Windows and
 
 On systems where environment variables are case-sensitive, the variable names may be all lowercase or all uppercase.  The lowercase names are checked first.
 
-The proxy server may be a hostname or IP address, optionally followed by a colon and port number, or it may be an http URL, optionally including a username and password for proxy authentication. The URL must be start with `http`, not `https`, and cannot include any text after the hostname, IP, or port.
+The proxy server may be a hostname or IP address, optionally followed by a colon and port number, or it may be an `http`, `https`, `socks4`, `socks4a`, or `socks5` URL. The URL cannot include any text after the hostname, IP, or port. If a scheme isn't specified, `http` is assumed.
+The URL may optionally include a username and password for proxy authentication, but the password is ignored when using `socks4` or `socks4a` as the protocols have no support for password authentication.
+
+* **`http`**: `http://[username:password@]hostname[:port]`
+* **`https`**: `https://[username:password@]hostname[:port]`
+* **`socks4`**: `socks4://[username@]hostname[:port]`
+* **`socks4a`**: `socks4a://[username@]hostname[:port]`
+* **`socks5`**: `socks5://[username:password@]hostname[:port]`
+
  ]]></format>
         </remarks>
         <exception cref="T:System.ArgumentNullException">The value passed cannot be <see langword="null" />.</exception>
diff --git a/xml/System.Net.Http/HttpClientHandler.xml b/xml/System.Net.Http/HttpClientHandler.xml
index c6ef2c31f73..a0f8c8586f4 100644
--- a/xml/System.Net.Http/HttpClientHandler.xml
+++ b/xml/System.Net.Http/HttpClientHandler.xml
@@ -281,7 +281,7 @@ After NuGet package v4.3.2, the default value of <xref:System.Net.DecompressionM
       </ReturnValue>
       <Docs>
         <summary>Gets or sets a value that indicates if the certificate is automatically picked from the certificate store or if the caller is allowed to pass in a specific client certificate.</summary>
-        <value>The collection of security certificates associated with this handler.</value>
+        <value>One of the enumeration values. The default value is <see cref="F:System.Net.Http.ClientCertificateOption.Manual" />.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
diff --git a/xml/System.Text.Json/JsonSerializerOptions.xml b/xml/System.Text.Json/JsonSerializerOptions.xml
index 3662e7efb93..c8caf40013e 100644
--- a/xml/System.Text.Json/JsonSerializerOptions.xml
+++ b/xml/System.Text.Json/JsonSerializerOptions.xml
@@ -686,8 +686,10 @@ For more information, see [How to ignore properties with System.Text.Json](/dotn
         <summary>Gets or sets a value that indicates whether fields are handled during serialization and deserialization.
             The default value is <see langword="false" />.</summary>
         <value>
-          <see langword="true" /> if fields are included during serialization; otherwise, <see langword="false" />.</value>
-        <remarks>To be added.</remarks>
+          <see langword="true" /> if public fields are included during serialization; otherwise, <see langword="false" />.</value>
+        <remarks>This flag only enables serialization for public fields, as is the case for properties.
+                 Private members need to be opted into individually using the <see cref="T:System.Text.Json.Serialization.JsonIncludeAttribute" /> attribute.
+        </remarks>
         <exception cref="T:System.InvalidOperationException">This property is set after serialization or deserialization has occurred.</exception>
       </Docs>
     </Member>
diff --git a/xml/System/String.xml b/xml/System/String.xml
index 1b789b79215..99fa8231345 100644
--- a/xml/System/String.xml
+++ b/xml/System/String.xml
@@ -4364,6 +4364,8 @@ The following example demonstrates the <xref:System.String.CopyTo%2A> method.
           <format type="text/markdown"><![CDATA[
 ## Remarks
 The initial content of the destination span passed to `action` is undefined. Therefore, it is the delegate's responsibility to ensure that every element of the span is assigned. Otherwise, the resulting string could contain random characters.
+
+To support interop scenarios, the underlying buffer is guaranteed to be at least 1 greater than represented by the span parameter of the action callback. This additional index represents the null-terminator and, if written, that is the only value supported. Writing any value other than the null-terminator corrupts the string and is considered undefined behavior.
  ]]></format>
         </remarks>
       </Docs>