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• [Option / Result / Vec / typle : basically we are interested in only inner values of the container

  
  

  Code Block
  language bash
  [ { "type": "Option", "item_type": { "type" : "bool" } }, { "type": "Result", "item_type": { "type": "int", "mode": "CompactFourByte" } }, { "type": "Vec", "item_type": { "type": "bool" } }, { "type": "tuple", "items": [ { "type": "int", "mode": "CompactFourByte" }, { "type": "Option", "item_type": { "type" : "bool" } } ] } ]

  
  

3. Custom containers 

• Structures: in structures declare definitions inline for built-in types and declare a reference for custom types 

  
  

  Code Block
  language bash
  { "type": "struct", "name": "Foo", "codec": "SCALE", //possible values SCALE or JSON "properties": [ { "name": "enabled", "definition": { "type": "bool" } }, { "name": "id", "definition": { "type": "struct", //reference to other struct "struct_name": "Id" } }, { "name": "counter", "definition": { "type": "int", "mode": "FixedWidth" } } ] }

  
  

• Enums: similar to Structures but also every variant of enum has a discriminator that used in Scale. By default based on 0, but can be overriden by attributes

Alternatives

Present at least two alternatives to the solution you suggested

Concerns

Write down all the things that worry you or other stakeholders

Assumptions

Document any assumption that you made

Risks

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Additional Information

1. Scale codec description in Substrate docs [https://substrate.dev/docs/en/knowledgebase/advanced/codec]
2. Scale codec Github page [https://github.com/paritytech/parity-scale-codec]