An assembly is a collection of items needed to complete a particular unit of work. Assemblies enable you to take off multiple items with a single operation. Another advantage is that you can obtain a cost per unit for a group of items. There are two kinds of assemblies:

• Standard database assemblies are stored in the standard database and can be used in any estimate based on that standard database.
• One-time assemblies are stored with the estimate and cannot be used in other estimates. (Later on, if you decide you want to use a one-time assembly in other estimates, you can easily change it into a standard database assembly.)