{
  "http://not-a-known-code-system" : null,
  "http://example.org/some-system|null" : null,
  "urn:ietf:bcp:13|null" : null,
  "http://unstats.un.org/unsd/methods/m49/m49.htm|null" : null,
  "http://example.org/system/code/sections|null" : null,
  "http://example.org/system/code/questions|null" : null,
  "http://not-a-known-code-system|2.36" : null,
  "http://example.org/some-id-type-system|null" : null
}