SHOULD

SHOULD declare enum values using upper snake case format

enum and x-extensible-enum values SHOULD be in UPPER_SNAKE_CASE format.

Invalid Example

schema:
  measurement:
   type: string
     x-extensible-enum:
       - Standard
       - Metric
       - Imperial
       - Non-standard

Valid Example

schema:
  measurement:
   type: string
     x-extensible-enum:
       - STANDARD
       - METRIC
       - IMPERIAL
       - NON_STANDARD

Zalando Guideline 240

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Published: 24 January 2025
Last updated: 14 August 2025
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