The subsystem archetype mentioned in:
https://docs.jboss.org/author/display/AS7/Extending+JBoss+AS+7
lives here:
https://github.com/kabir/archetypes/tree/master/jboss-as-subsystem-archetype.
Pete, please get in touch before you release your EE 6 archetype so we can sync the
tagging, since it should live under:
https://github.com/jbossas/archetypes.