Hello,
Today we have received a new iteration of JAR with one line I find cryptic. 
“These abilities are considered missed if a player did not acknowledge them in any way at the point that they should have occurred.”
The word “occurred” disrupts me. Is it the moment the ability triggered? Is it the moment the ability should have resolved? is it the moment it's effect has impact on the visual state of the game as in IPG?
A little more detailed clarification would be nice. 
Thank you.

From the MTR (which applies at all RELs):

“Triggered abilities are considered to be forgotten by their controller once they have taken an action past the point where the triggered ability would have an observable impact on the game. Triggered abilities that are forgotten are not considered to have gone onto the stack.”

So it's the same guidance you use for Comp REL triggers, looking for acknowledgement at the first time they become relevant to the visible game state. You don't use the IPG at all, but instead use the guidance for a forgotten trigger from the JAR, after determining it was missed based on the MTR definition.

Edited Josh Stansfield (April 23, 2013 10:26:30 PM)

This is the part I find confusing:

These abilities are considered missed if the player did not acknowledge them in any way at the point that
they should have occurred. If the ability includes the word “may,” assume the player chose not to perform it.
Otherwise, add it to the stack now unless it happened so long ago that you think it would be very disruptive
to the game.

Is there any time limit on remembering the triggers? I played a Zendikar draft on the weekend and my opponent continually forgot his Blood Seeker triggers. If we're both at 20 life, can my opponent 4 turns later say, “Hey, I forgot that Blood Seeker trigger. Lose 1 life.” Unless I was at very low life, can you argue that it would be very disruptive to the game? It would seem to me this should have a 1 turn limit on it.

You'll just have to use your discretion. I think 4 turns is “so long ago” that it's probably too late. Less than a full turn later is almost always soon enough. I think there's no specific time limit so things like Obzedat can come back even if forgotten for a while, and forgotten Angel of Serenity death trigger can resolve when noticed. Also, occasionally even one turn can be too long if the trigger would cause a major disruption if it resolved now.

So do what feels right to you (and hopefully also makes sense to the players).

Edited Josh Stansfield (April 23, 2013 11:05:53 PM)

There is some intentional flexibilitiy left in the way that missed triggers should be handled at regular REL, which is alluded to in the introduction part of the JAR - there is a different atmosphere and environment in different play groups, and you should use your judgement to decide what is appropriate way to handle them given your play group. If you are in a more educational group, then you are going to be a lot more flexible on when you allow triggers than if you are in a more competitive group, for example.

What if a player remember about his trigger during turn-based action? Should we put the trigger onto the stack before or after the action?

For example. A player forgot about the trigger from his Pyreheart Wolf. His opponent is trying to block with a single creature. The player realizes that he fogot the trigger. We are ready to add it the stack now. Where is this “now”?

If a player points out Pyreheart Wolf's trigger while their opponent is blocking they are bringing attention to it when it would have an “observable impact on the game” so wouldn't be classed as missed.

Originally posted by Gareth Tanner:

If a player points out Pyreheart Wolf's trigger while their opponent is blocking they are bringing attention to it when it would have an “observable impact on the game” so wouldn't be classed as missed.

Dear Gareth, show me words “observable impact on the game” in JAR.
We are talking about Regular REL and unexpienced judges, who never saw IPG at all.

These abilities are considered missed if the player did not acknowledge them in any way at the point that they should have occurred.

As Josh pointed out, MTR section 4.4.:

"Triggered abilities are considered to be forgotten by their controller once they have taken an action past the point where the triggered ability would have an observable impact on the game. Triggered abilities that are forgotten are not considered to have gone onto the stack."

This also applies at Regular.

Edited Philip Ockelmann (April 24, 2013 11:52:17 AM)

Thanks all for replies, Josh and Kim, things you pointed pretty much cover all questions that rise.
It feels natural that Regular tournaments are used to educate players and should follow similar guidelines as Competitive in regards of triggers, but the words used in JaR in comparison to terms like “triggered/resolved” and the more recent one “observable impact” were confusing.