In addition to item modifiers (that add additional items to the item), you can assign modifiers of the type Time modifier and Text modifier to the item.
Text modifiers
Text modifiers are predefined texts that are set up in advance to go with certain kinds of items, and are assigned to these items in the same way as item modifiers.
Time modifiers
Time modifiers are text modifiers with the addition of a numeric field that is used to add to or subtract from the item’s production time.
See also
How to: Assign Text and Time Modifiers to Items