Okay, so since we have two very different Forbidden & Limited Lists coming up (one for TCG, one for OCG), it is anticipated that people will want to play both of these formats. The issue here is that in each version of the game, some cards are exclusive to that version (TCG-exclusive, OCG-exclusive). Additionally, there may be issues with Percy's cardpool, and DN is fully manual, so as of the writing of this post, there is no such TCG/OCG distinction tagged on DN itself. Therefore, my goal today is to help you help yourself identify exactly what constitutes each. This announcement will not cover TCG North America vs TCG everywhere else; for all intents and purposes, we are treating the entire TCG as having the same cardpool, and the entire OCG as having the same cardpool.

TCG/OCG Legal
Any card that has both a TCG and an OCG version. This will include most cards released in a booster set that is out in TCG and OCG territories. The most recent set as of the writing of this post that fits this qualification is Judgment of the Light. Additionally, an OCG-exclusive Promotional Card that is later released in the TCG via a booster set, tin or some other means will also become TCG-legal (an example: Shock Master). TCG-exclusive cards released in booster sets are introduced to the OCG via Extra Packs; the most recent set for which this has happened is Lord of the Tachyon Galaxy (this means any TCG-exclusive card released in Judgment of the Light is not legal in the OCG as of the writing of this post).

TCG-Exclusive
This mainly applies to any card released between numbers 081 and 090 of a booster set, and for which an Extra Pack containing them has not been released in the OCG. These cards are legal for play in the TCG, but not the OCG. As of the writing of this post, Judgment of the Light is the set for which this holds true (example: Noble Knight Drystan).

OCG-Exclusive
This mainly applies to OCG Promotional Cards that do not have a subsequent TCG release, as well as some other older cards that just haven't been given a release in the TCG yet (examples: Sixth Sense, Kamionwizard, Vulcan the Divine). Also, this applies to booster sets and Structure Decks that have an OCG release, but no corresponding TCG release. As of the writing of this post, Shadow Specters fits that criterion, so any card that has its only release in Shadow Specters is not TCG-legal until that card is released in the TCG. Maiden with Eyes of Blue is another example of an OCG-exclusive card until the Structure Deck containing it is released in the TCG.

How to Verify Legality
If there are any doubts you have as to whether a card you want to use is TCG or OCG, there are some other methods you can use.

• Google Search
  
• Yu-Gi-Oh! TCG Card Database: http://www.db.yugioh-card.com/yugiohdb/?request_locale=en
  
• Yu-Gi-Oh! Wikia (note that while it is a reliable site as long as it hosts sources, not everything on there is accurate; for example, Vulcan the Divine is still OCG-only as of the writing of this post)
  
• Ask whoever is hosting your event about the card (this means I will be expecting Event Managers to learn this material especially well)
  

Conclusion
I realize that this guide probably hasn't covered everything regarding distinctions between the two, but this should be useful for most practical purposes. Feel free to ask if you have any questions concerning this topic.

Marked as global announcement, I hope this explains to people things and justify what RDA's going to follow.