: This is often used as a "tag" in community-shared archives. In various contexts, it can stand for MusicBrainz (if the file contains audio-related images) or a specific release group/uploader's initials.
: This indicates the archive contains a full set of files ("all Part") that were either captured or curated as "new" in the year 2010 . The Story of the Archive
In 2010, at the height of the digital camera boom, a user likely compiled their entire year's worth of memories—possibly from a new Sony camera—into a single compressed volume for safe-keeping or sharing.