In many situations, you cannot determine ahead of time the parts and subassemblies in the final design. For example, consider a company that designs consoles for control rooms and operation centers. Each customer has unique requirements that necessitate unique designs and solutions. One customer requires one small console with space for three operators and their associated equipment. Another customer requires multiple consoles of various designs to accommodate a large number of people and equipment.
In this type of solution, it is impossible for the Inventor ETO solution author to anticipate every possible configuration. The top-level design does not include all of the necessary child rules, because there is no typical solution. It requires a more flexible solution than for single models.
When you build models with multiple, configurable parts and subassemblies, the Intent author builds a solution in which you interactively add children to the top-level assembly. In this solution, the top-level Intent design includes parameters that pertain to the overall design, such as customer information, material type, and so on. It does not contain all of the necessary child rules. Therefore, when you start a new assembly using the top-level design, the assembly is empty. You add the required designs by dynamically adding child rules to the assembly file, selecting from designs that are made available by the solution author.