Stackable
In NetHack, many varieties of items can stack into one inventory slot. This includes:
- gems
- potions
- scrolls
- comestibles
- projectiles, like arrows or darts
- some throwable weapons, like daggers, spears, and boomerangs
Besides conserving on inventory space, getting items to stack is important for efficiency when using holy water to bless items, or using a scroll of enchant weapon to enchant an entire stack of arrows.
In order for objects to stack, their beatitude, enchantment, and erosion status must be exactly the same. Additionally, even a subtle difference in identification status can affect whether or not something stacks. For example, if you have two daggers, and only drop one on an altar and see it was uncursed, those two daggers will no longer stack. Then, if you were to go a step further, and use a scroll of identify on the dagger you didn't drop, and it was an uncursed +0 dagger, then it would no longer stack with your plain "uncursed dagger".
Besides affecting the ability to bless/enchant multiple objects at once, it also can affect how many projectiles were fired. A player can only get off multiple shots in one turn if the projectiles are from the same stack.
There are occasions, however, where one may want to get a stack to split. The way to achieve this is to name the stacks separately. For example, a starting rogue may desire to both keep one of his starting stack of daggers as a main weapon, and have the rest of the stack serve as projectiles. The way to do this would be to name the entire stack, e.g., "Throwing", and drop all but one. Then, name the last one still in the inventory to e.g., "Main". Then you can pick up the others and they will be separated. It is not sufficient to name them, drop all but one, and then clear out the name for the one in hand - stacks will always take on a name if they do not already have one. This phenomenon can often be observed early on, when one finds an orcish dagger, has the pet BUC test it, and then names it uncursed, only to see other new daggers stack with it.
This naming tactic is also useful when someone needs to split up a stack of water to make an initial unholy water by reading while confused a blessed scroll of remove curse. It may be tedious, but it is probably wise to split up around 10 stacks for this purpose.
Getting potions to stack is of the utmost importance in alchemy. All alchemy results will be "diluted potion of X", and since diluted potions will only stack with other diluted potions, it can be advantageous to dilute (by dipping once) every potion a player finds at the first opportunity. It won't affect the qualities of the potion, and it is generally easier to do as one traverses the dungeon as the fountains near your stash won't last forever. Just take care to have identified acid, as dipping acid will cause an explosion.
