The important distinction
In the named reference, queens, jacks and diamonds form the fixed trump group. For following suit, a queen or jack belongs to trump rather than its printed suit.
Ask two separate questions
During an open-hand practice, first identify the card’s playing group. Then consult the source to determine which cards are permitted in response. A comparison of cards already played cannot answer what a player was allowed to choose from an unseen hand.
Use the tools carefully
The card explorer labels every card’s playing group. The trick examples compare five face-up cards. They do not know the remaining hands, a reserved called card or any special concealed card arrangement.