References.yml

-
    # Set a new reference with a value specified manually
    # (note that custom references can be set as well via options in the `migrate` command line)
    type: reference
    mode: set
    identifier: xxx # name of the reference to set
    value: zzz # value for the reference.
               # It can be a scalar or an arbitrarily nested array
               # It can be a Symfony configuration parameter by using the syntax '%name%'
               # It can be an environment variable by using the syntax '%env(name)%'
               # NB: in this case variables set by Symfony's .env mechanism are not supported
    overwrite: true|false # Optional, default false. If not set, and the reference already exists, an exception is thrown
    resolve_references: true|false # Optional, default true. Use this to avoid reference resolution for 'value'

-
    # Load a whole set of references from a json or yaml file
    type: reference
    mode: load
    file: xxx # path to the file to load. It must have an extension of .yml or .json, and respect that syntax.
              # It can be an absolute path, or relative to $DIR_OF_MIGRATION_DEFINITION/references/ folder.
              # NB: if found, the token '{ENV}' will be replaced with the current Symfony environment, eg:
              # ezpublish/config/migrations_{ENV}.yml will become ezpublish/config/migrations_dev.yml
              #
              # The format for the contents of this file is: an array of reference-key => reference-value
              # The reference-value can be a Symfony configuration parameter by using the syntax '%name%'
    overwrite: true|false # Optional, default false. If not set, and any reference already exists, an exception is thrown

-
    # Save the complete set of references currently defined to a json or yaml file
    type: reference
    mode: save
    file: xxx # path to the file to load. It must have an extension of .yml or .json.
              # It can be an absolute path.
              # NB: if found, the token '{ENV}' will be replaced with the current Symfony environment, eg:
              # ezpublish/config/migrations_{ENV}.yml will become ezpublish/config/migrations_dev.yml
              #
              # The format for the contents of this file is: an array of reference-key => reference-value
              # The reference-value can be a Symfony configuration parameter by using the syntax '%name%'
    overwrite: true|false # Optional, default false. If not set, and the file already exists, an exception is thrown

-
    # Dumps a reference to STDOUT. For debugging purposes
    type: reference
    mode: dump
    identifier: xxx # Name of the reference to dump. must include the 'reference:' prefix
    label: string # optional. If present, it will be printed instead of the reference name