Synopsis. Draft from a working discussion, to be expanded.

Two layers, one rule

The DBJ Taxonomy is a single tree. The top level is an ordered list of abstractions: Conceptual, Logical, Physical, Implementation. Below it sit the capabilities. Every item has exactly one place in that tree, and the place is its stable ID.

That is the whole core. It is deliberately small, and nothing in it is optional.

Around the core, an organization may attach a tagging matrix. It is guidance, not part of the taxonomy. Tags describe an item; they never decide where it lives. A book in a library can carry any number of tags, but its shelf does not depend on any of them.

What is an item

An item is a Product: a software product, a service, documentation, a physical book. The core does not say more than that, and does not need to. What a Product is, and what the organization produces, is declared by the business. The taxonomy only gives it a place.

The tagging matrix is a shipping log

“shipping log” is the detailed matrix like template populated. For an item already located by DBJ Taxonomy.

The matrix template is described in An Item, Five Facets View, a non-trivial use case for advanced users.

Think of the matrix as the shipping log attached to a Product. Each organization decides how much goes into it:

  • Minimal: the Product’s place in the tree, plus one or two attributes (for example owner).
  • Elaborate: Segment, Lifecycle stage, cross-cutting concerns such as Security, Integration and Data Management, each with the organization’s own values.

Segment and Lifecycle are attributes, not classification. Lifecycle in particular is private to the organizational unit in which a project is rotating, so a shared core cannot define it.

Why not put all of it into the core

A model with five independent facets can not be drawn as one hierarchy. It has no single canonical location for an item, and it invites the “tag” to become an escape route to anything.

A single tree is simpler and stricter. But simplicity is not understood immediately. It takes maturity, and organizations that never had to classify with one logic find it hard.

So the matrix stays optional and comes second: an item is first placed by the tree, and only then, if the organization wants, detailed with the matrix.

Maturity

This is the same reasoning behind the DBJ CMM Level 5 “entry ticket”. An organization must be mature enough to loop through the BPT at the speed of AI. Simplicity is the prize for that maturity, not a starting point.

Rule of thumb

  • Where an item lives: the core, one ID.
  • What else is known about it: the tagging matrix, as much or as little as the organization can sustain.
  • Tags never move an item.