%YAML 1.1
---
$schema: "http://stsci.edu/schemas/yaml-schema/draft-01"
id: "http://stsci.edu/schemas/gwcs/wcs-1.4.0"

title: >
  A system for describing generalized world coordinate transformations.
description: >
  ASDF WCS is a way of specifying transformations (usually from
  detector space to world coordinate space and back) by using the
  transformations in the `transform-schema` module.
type: object
properties:
  name:
    description: |
      A descriptive name for this WCS.
    type: string

  pixel_shape:
    description: |
      The optional shape of the data that the WCS applies to as an array
      in ``(x, y)`` order (where for an image, ``x`` is the horizontal
      coordinate and ``y`` is the vertical coordinate) or ``None`` if not
      defined for this WCS.
    anyOf:
      - type: 'null'
      - type: array

  steps:
    description: |
      A list of steps in the forward transformation from detector to
      world coordinates.
      The inverse transformation is determined automatically by
      reversing this list, and inverting each of the individual
      transforms according to the rules described in
      [inverse](https://asdf-standard.readthedocs.io/en/latest/generated/stsci.edu/asdf/transform/transform-1.4.0.html#inverse).
    type: array
    items:
      tag: tag:stsci.edu:gwcs/step-1.*

required: [name, steps]
additionalProperties: true
...
