The Yugioh Tournament Policy document, the Yugioh FAQ, nor the Official Yugioh Rulebook address the issue of markers for card effects. Alex Charsky the UDE Judge Manager is making an effort to unify UDE distributed games whenever possible, with that in mind please see the following thread for additional discussion....
http://entertainment.upperdeck.com/COMMUNITY/forums/1/926913/ShowThread.aspx
If you don't want the whole discussion and wish to cut to the Alex's comments.....
<Quote Alex Charsky>
Here is the official answer to the treeborn frog question.
Remembering optional trigger effects is part of skill testing within the game. Players may not use visual aids to remind them.
Remembering mandatory trigger effects (such as Sacred phoenix) is the responsibility of both players, so players are allowed to use visual aids (such as turning the card sideways) and even notes to remind them of its effect.
As a bonus, here's the official answer to the removed from play zone question.
Please don't mix the removed from play zone with the graveyard zone. It's just too easy to mess up the game by having those cards in the same pile. Please start a new pile for the removed from play zone. I realize that occasionally there is very little space for players to operate in. In those cases, if players truly can't figure out a effective space to place their removed from play pile, then they should call for a judge to help them.
Alex Charsky
Judge Manager
Upper Deck
Writing notes and using visual aids (turning card sideways, dropping dice on it) to remind players of optional triggers are two different things. This still applies. Now, however, you are able to write frog on your score pad, if you think that that would help you to remember the optional trigger.
Notice that it's acceptable to use visual aids to remember mandatory triggers.
Alex Charsky
Judge Manager
Upper Deck
Yu-Gi-Oh! RK3
PM L3
TO L1
Specialist L1