The following improvements were identified by reading Cadence Core Contracts with CCF specs and codec in mind.

More types need to be added in CDDL:

• struct interface type
• resource interface type
• contract interface type
• reference type
• restricted type

Reassign tag numbers to reserve some tag numbers in each (sub)group.

Add interface types as options to ccf-composite-type-message. This is more extensible than using simple type at the cost of encoding a little more data.

Add reference and restricted types as options to inline-type.

Add support for function value.

Refactor CDDL to separate type objects from type value objects for readability and cleaner implementation.