doc: design_www: document offline friendliness

This isn't anything new and has been a part of the design
since the beginning, but it may not be apparent to some
folks.

diff --git a/Documentation/design_www.txt b/Documentation/design_www.txt
index 240fa5046b35bc12a3dad7aca7d567d376e6a609..b1f916ddb3697606aaf623ada2ef3b607666e6f3 100644 (file)
--- a/Documentation/design_www.txt
+++ b/Documentation/design_www.txt
@@ -77,6 +77,23 @@ installed to render uncommon characters.
 Plain text (raw message) endpoints display in the original encoding(s)
 of the original email.
 
+Offline friendly
+----------------
+
+The "/t/", "/T/", "t.mbox.gz" endpoints are designed to be
+useful for reading long threads for users with intermittent
+connections or saved for offline viewing.
+
+Date displays are always absolute, not the "X hours ago"
+pattern commonly seen because readers may be reading a
+previously-saved or cached copy.
+
+HTML URLs end with '/' or "$FILENAME.html".  The reason many
+URLs end with the '/' character is so it can trivially be saved
+to a directory via wget or similar tools as "index.html", making
+it easy to mirror all files ending in ".html" using any static
+web server.
+
 Guidelines for using limited HTML
 ---------------------------------