No select multiple in backend?

authors: Array

title: Text Beitrag
@extends:
    type: default
    context: blueprints://pages

form:
  fields:
    tabs:
      fields:
        content:
          fields:
            header.authors:
               type: select
               multiple: true
               label: Author(s)
               options:
                  a: A 
                  b: B
                  c: C
                  d: D

            header.authors:
              type: select
              multiple: true
              label: Author(s)
              options:
                a: A
                b: B
                c: C
                d: D
              validate:
                type: array

authors:
    -
        - a
    -
        - c
    -
        - d