The model structure of the Pivot model is defined in PivotStuctural.ecore complemented by constraints in Pivot.ocl.
The /org.eclipse.ocl.examples.build/src/org/eclipse/ocl/examples/build/GeneratePivotModel.mwe2
script supervises their merge to Pivot.ecore and the generation of the Java via Pivot.genmodel.

Vintage UML-aligned content below...


Sources:

Infrastructure.cmof - from UML 2.2 specification
SubSuperstructure.cmof - trimmed and edited from UML 2.2 specification
OCL.cmof - from OCL specification after editing and enhancement
MDTOCL.cmof - local contribution
Pivot.cmof - the overall merge
Pivot.genmodel

Pivot.cmof defines:
- the merge of
--- UML Core::Basic from Infrastructure.ecore (standard)
--- UML Core::PrimitiveTypes from Infrastructure.ecore (standard)
--- UML-based Templates from SubSuperstructure.ecore
--- UML-based Associations from SubSuperstructure.ecore
--- OCL PrimitiveTypes (adds Real for now)
--- OCL Types (potentially standard)
--- OCL Expressions (potentially standard)
--- OCL Runtime (new standard perhaps)
- the Ecore profile
--- the URI
--- the primitive type to Java mappings

A UML Editor->Package->Merge... is saved as Pivot.merged.uml

Pivot.genmodel is Reloaded from Pivot.merged.uml to produce pivot.ecore.
-- the genmodel reload shows pivot as the ONLY package.

This is all automated by the /org.eclipse.ocl.examples.build/src/org/eclipse/ocl/examples/build/GeneratePivotModel.mwe2
workflow.