ID works fine. What he maybe meant is that lanterns have EASY_KNOW flag. This means that lanters that don't have special powers will show their level requirement instead of a question mark:
Most items don't have EASY_KNOW flag and will look like this when you find them:
Unknown dagger {+,?} <- question mark instead of level indicates that you don't know if it's got special powers or not, until you use ID.
Lanterns have EASY_KNOW flag and will look like this:
Unknown brass lantern {+,3} <- you know right away that this lantern has NO special powers, because it shows the level.
Unknown brass lantern {+,?} <- you know that this lantern MUST have special powers, because it doesn't show level.
So whenever you find a lantern with '?' for level requirement, make sure to pick it up!
In general, all items that cannot have any random enchantments or abilities on their base version, have EASY_KNOW flag.
Eg. Ring of fire resistance has EASY_KNOW. Ring of Protection does not, because it has a random +AC value, so you need ID to find out.
Hmm, I might add this to the guide..
