Each message stack contains several different types of cards:
The first card is the menu card, which allows the user to choose what operation to perform. The second card is the filter card, which lets the user select a criteria to filter messages by. The third card is where new messages are created. If they're OKed, the contents are copied into a regular message card. The fourth card is a master template for the message cards; this empty message card ensures there's at least one message card even when the section is empty. The rest of the stack is composed of message cards.