Wren uses titles. Wren doesn't differentiate between an "article" and a "note" the way that my other web publishing apps do, such as Junco, Grebe, Scaup, and Veery.
For those other web apps, I borrowed from the Indieweb gang where a note is simply a post without a title. Those other apps support Markdown and Textile, especially the latter, since I've been writing in Textile since 2005.
But this winter and now spring I have tried to write more using Markdown and to simplify my post formatting process. Wren truly simplifies by eliminating formatting commands that I have used in my other apps.
Anyway, I could create my own style guide regarding notes in Wren by starting the title with "Note:" followed by some kind of standard format for date and time. That's good enough for a title.