From the introduction:
These cards are 2 x 3.5 inches and fit on Avery 8371 sized business cards.
The cards are designed to be double-sided, with the letter on one side and “SafetyToolsCardsBack.png” on the other.
Safety Tools Cards present print-and-play N, O, and X cards. They are distributed with a one-page DOC "print guidelines", a 1-page PDF card back document, and three 1-page card documents.
X, N, and O cards are check-in tools. They can be used by tapping physical cards, typing the letter in the chat function of the video conference software or virtual tabletop you are using, or using hand signals. Before the game begins, remind everyone that they are available and how to use them.
The X card can be used at any point if a participant is uncomfortable with the content happening in-game. When the X card is used by tapping the card or typing an “X” in the chat, the group can change, rewind, or skip the content.
The N card can be used at any point if a participant feels like they are headed towards an X. When the N card is used by tapping the card or typing an “N” in the chat, the group can change the content or have the scene “fade to black.”
The O card can be used at any point if a participant wants to continue with the content. When the O card is used by tapping the card or typing an “O” in the chat, the group is ok to continue with the content. They can also regularly be prompted by a “O?” asked out loud or in the chat to check-in if everyone is still ok.