I like your suggestion, and have not heard that idea on here before. But in the meantime, there's another way, which you probably already know, because this is not inside the character sheet so it's not exactly what you asked, but has the same functionality. The GM can make a new empty journal for any player (one for each player if you want). Call this journal Player 1's Private Journal to the GM... Player 2's Private Journal to the GM... and so on. Give permissions as you want it: Player 1 & the GM. Player 2 & the GM. Etc. Yes it's another step of work to set these up, and it's outside the character sheet (though nearby). This way you can keep the actual Character Sheets viewable to All Players but only make the private journals for the individuals. By the way another method is, use a combination of Private Messages (GM and a Player only), and Forum Posts (viewable to all) on the Campaign Details outside the game table. This is actually the method I use IMC for backstories and notes/requests from players to GM. Your suggestion is still valid.