openapi: 3.0.0
info:
  title: A version and revision matrix parameter
  version: 1.0.0
paths:
  /{version}{rev}/customers:      # https://api.example.org/v2;rev=2/customers
    parameters:
    - name: version
      in: path
      required: true
      schema: 
        type: string
    - name: rev
      in: path
      required: true
      style: matrix
      schema:
        type: integer