Network definition in version 3.0 docker-compose file

I have the following network definition in my compose file:

    driver: bridge
    enable_ipv6: false
      driver: default
      - subnet:

which works nicely using version 2.1 file version. However when I change the file version to 3.0 I get the following error when trying to start the compose file:

ERROR: The Compose file ‘./docker-compose_wasfp11_cf13_gbg_1.yml’ is invalid because:
networks.wp_bridge_network_int value Additional properties are not allowed (‘enable_ipv6’ was unexpected)

Docker & compose are at the following level:
root@docker2:~/compose$ docker-compose -v
ddocker-compose version 1.11.2, build dfed245
root@docker2:~/compose$ docker -v
Docker version 1.13.1, build 092cba3

Is this a bug or am I doing something wrong here?