Core spec authoring checklist

• Syntax
  • Exact heap types (#93)
  • Descriptor types (#99)
  • Exact function externtypes (#102)
  • Instructions
    • struct.new_desc and struct.new_default_desc (#101)
    • ref.get_desc (#104)
    • ref.cast_desc_eq, br_on_cast_desc_eq, and br_on_cast_desc_eq_fail (#105)
• Validation
  • Exact heap types ok and subtyping (#97)
  • Descriptor types ok and subtyping
  • Exact function externtypes ok and subtyping (#102)
  • Instructions
    • Relaxed br_on_cast and br_on_cast_fail(#92)
    • Restrict struct.new and struct.new_default to types without descriptors (#101)
    • Make allocation instruction results exact (#103)
    • struct.new_desc and struct.new_default_desc, including as constant expressions (#101)
    • ref.get_desc (#104)
    • ref.cast_desc_eq, br_on_cast_desc_eq, and br_on_cast_desc_eq_fail (#105)
• Execution
  • Descriptors in struct instances
  • Function instances valid with exact externtypes
  • Instructions
    • struct.new_desc and struct.new_default_desc
    • ref.get_desc
    • ref.cast_desc_eq, br_on_cast_desc_eq, and br_on_cast_desc_eq_fail
• Binary format (#108)
  • Exact heap types
  • Descriptor types
  • Exact function externtypes (#102)
  • Instructions
    • struct.new_desc and struct.new_default_desc
    • ref.get_desc
    • ref.cast_desc_eq, br_on_cast_desc_eq, and br_on_cast_desc_eq_fail
• Text format
  • Exact heap types
  • Descriptor types
  • Exact function externtypes (#102)
  • Instructions
    • struct.new_desc and struct.new_default_desc
    • ref.get_desc
    • ref.cast_desc_eq, br_on_cast_desc_eq, and br_on_cast_desc_eq_fail
• Appendix
  • Exactness type variables for principal types
  • Validation algorithm
  • Change history
• Indices
  • Types
  • Instructions
  • Semantic rules
  • Index ("exact", "desctype", "descriptor")

Review the checklist in issue #94 together with the referenced work items (#92, #93, #97, #99, #101, #102, #103, #104, #105, and #108). Done means completing the remaining syntax, validation, execution, binary format, text format, appendix, and index entries for the custom descriptors core specification.