Certain cards are so important that they must always be saved in normal situations, and discarding them promises that the duplicate is elsewhere in the hand.
These are known as Elimination Notes, which are slowly reduced as more information is learned.
Elimination notes are only written when:
a delayed playable card (or 2) is called to discard
a delayed playable card (or 2) is given Permission To Discard while there were 2+ clues
If elimination notes for a playable identity are reduced to a single card, even if it has 0 positive clues, that player is Loaded and is expected to play that card.
Otherwise, elimination does not apply.
Alice discards a playable r3 from PTD, resulting in Elimination Notes for the second copy of r3 in slot 2. Alice is now Loaded.
A Gentleman's Discard can be performed even if the duplicate isn't in the rightmost position as long as all possible positions until the duplicate (from the right) are playable.
This is known as a Layered Gentleman's Discard, since the duplicate is layered behind the other playable cards.
Bob can perform a Layered Gentleman's Discard discarding g4, which causes Alice to play p2 and then g4.