This is a simple mod that adds an activator to Shadowmarks, allowing you to look at a glance to see the name of the mark. Activating it gives you a quote from the in-game book Shadowmarks. Text placement is done dynamically, meaning any mods that place Shadowmarks in the world should properly display themselves without compatibility patching, as long as they use an existing Shadowmark TextureSet.

Until you find the in-game book Shadowmarks, or join the Thieves' Guild, you won't be able to read Shadowmarks, and they'll only look like strange symbols to you. If you really can't be bothered to find the book, or do one quest, you can spawn the book with the console, or use the command:

set ShadowmarkBookObtained to 1