Core Sets
Base sets of tournament cards with larger pools of mostly reprints.
Expansions
Expert-level tournament sets.
Command Zone
Commander/EDH, Planechase, and other sets that use the command zone.
Reprints
Sets that contain only reprinted cards.
Supplemental
All other non-Standard printed sets designed to supplement the game.
Digital Sets
Digital-only sets and releases with no print companion.
Beginner Sets
Preconfigured sets and decks geared towards new players.
Premium Sets
Collectable, foil, or other special printed sets.
Promos
Promotional sets or cards included in other media or advertisements.
Standalone
Experimental, out-of-world, draft inovative, or other releases that can be played on their own.
Alternatives
Other official versions of set symbols used by WOTC.
Custom
Symbols I've created to fill in gaps and other game needs. Other unofficial symbols are incorporated and tagged above.