!

A green exclamation point next to an item in your INVENTORY EQUIPMENT or
in a CONTAINER means you have already used IDENTIFY to learn about that
item. You can now use the APPRAISE command on it to refresh your memory
about what it does or to show it to someone else, without using another
identify SCROLL or your MANA

Exclamation points in certain areas of the game (including IDENTIFY and
AUCTION mean "anti," such as M or !mage for equipment that is
"anti-mage," not usable by people of that class. !E, !G, and !N mean
anti-evil, anti-good, and anti-neutral, and so on.

The exclamation point can also be used as a command by itself to
repeat the last command you sent to the game, whatever it was.

See Also: APPRAISE IDENTIFY SHORTCUTS