So simple they will never change
  UncheckedUrl
  Url
  RelayUrl
  Unixtime
  SubscriptionId
  MilliSatoshi

Very unlikely to need versioning due to being fixed by the protocol
  Signature (uses a type that is the raw sequence of bytes)
  PublicKey (is the raw bytes)
  PublicKeyHex
  Id (bytes)
  IdHex
  EventKind (just a u32)

Never serialized
  Span
  ContentSegment
  ShatteredContent
  EventDelegation
  ZapData
  PayRequestData
  EventKindOrRange

Dont version right now
  Filter (defined structure that only uses types that aren't versioned)
  EventAddr
  EventReference
  EventPointer
  Profile
  NostrBech32
  NostrUrl
  DelegationConditions

Versioned:
  RelayLimitation
  RelayRetention
  Fee
  RelayFees
  RelayInformationDocument
  SimpleRelayUsage
  SimpleRelayList
  Nip05
  Metadata
  Tag (due to changing fields in enum values)
  Rumor (due to Tag)- might not be serialized, but has speedy
  PreEvent (due to Tag)- might not be serialized, but has speedy
  Event (due to Tag)
  RelayMessage
  ClientMessage