When the rate of change increases to the point that real time required to assimilate change exceeds the time in with change must be manifest, the ent… - John Zachman

It is not adequate merely to produce running code. In the long term, enterprise value lies in the models themselves. They have intrinsic value in their own right, as they constitute the baseline for managing change

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.

• Top down implies level of detail that is, looking at the highest level of summarization and then decomposing hierarchically to lower levels of detail as required.