Programme shape, gating decisions and dependency-ordered waves
The two gating decisions that define every Plex programme — topology and MES/QMS scope — the evidence needed to settle each, the dependency-ordered wave plan, the mode decision (big-bang versus plant-by-plant), team shape, discovery artefacts and go/no-go criteria.
What you will be able to do
Explain why topology and MES/QMS scope are one-way-door decisions that must be resolved before design freezes
Describe the evidence needed to settle the topology decision and the cost of settling it late
Sequence the eight canonical migration waves in dependency order with Plex-specific conditionals
Evaluate the big-bang versus plant-by-plant mode decision and its interaction with topology
Name the seven discovery artefacts that must exist before design freezes
Define go/no-go criteria for a Plex programme
Introduction
A Plex-to-D365 programme carries more upfront discovery than most ERP migrations, for one structural reason: the source documentation is thinner than any on-premises system in this hub. SAP has OBYC, JD Edwards has the AAI table, Infor M3 has published technical references — Plex has marketing pages and an unreachable developer portal.
The two gating decisions
Plex models multiple sites and plants inside one tenant with individual and roll-up reporting. D365 uses legal entities as the hard financial and security boundary, with sites and warehouses as sub-legal-entity logistics units.
The dependency-ordered wave plan
The eight canonical waves are ordered by referential dependency — each wave's data depends on the prior wave's artefacts already existing in D365. Plex introduces conditionals: waves that only apply if specific Plex modules are licensed.
The mode decision: big-bang versus plant-by-plant
The mode decision is not independent of the topology decision. Their interaction creates a decision matrix:
Team shape and key roles
[!TIP] The Plex application owner role is non-negotiable and cannot be filled by reading documentation — because the documentation does not exist at the level of detail this programme requires.
Discovery artefacts that must exist before design freezes
Seven artefacts must be complete and signed off before the programme moves from Discover to Decide:
Go/no-go criteria
[ ] Topology decision signed off (legal entity vs site, per plant) [ ] Module-licensing inventory confirmed with the Plex account team [ ] MES/QMS scope decision made (replace, retain with integration, or defer) [ ] GL export at line grain obtained and validated by the D365 financial architect [ ] Integration inventory complete and…
Knowledge check
Summary
A Plex programme is defined by two gating decisions — topology and scope — that must be resolved in explicit, evidence-based decision gates before any design work begins. The dependency-ordered wave plan follows the same eight-wave structure as any D365 migration, but with Plex-specific conditionals driven by module licensing.