• Top down implies level of detail that is, looking at the highest level of summarization and then decomposing hierarchically to lower levels of deta… - John Zachman

There is a set of architectural representations produced over the process of building a complex engineering product representing the different perspectives of the different participants.

The older disciplines of Architecture and Manufacturing have accumulated considerable bodies of product knowledge through disciplined management of the "product definition" design artifacts. This has enabled enormous increases in product sophistication and the ability to manage high rates of product change over time. Similarly, disciplined production and management of "Enterprise definition" (i.e. the set of models identified in the Framework for Enterprise Architecture) should provide for an accumulation of a body of Enterprise knowledge to facilitate enormous increases in Enterprise sophistication and accommodation of high rates of Enterprise change over time.

Decentralization without structure is chaos.