Descriptor forms

A descriptor is the right-hand side of a pairing. It takes one of five forms.

Form	Example	Meaning
Pointer string	"/a/b"	read from the current source
Relative reference	"../sibling"	resolve against the source path (Extended)
Name string	"mapping:Person"	reference a registered mapping
Object	{ "source": "/a", "as": "number" }	keyword descriptor
Array	["/a", "/b"]	alternatives; first defined result wins

A pointer string is the common case:

/title: /book/title

An object composes keywords into a pipeline:

/year: { source: /book/published, as: number }

An array tries alternatives per evaluation:

/name: ['/nickname', '/fullName']

Relative references belong to the Extended tier and resolve against the current source path; see the JSON Pointer profile.

Name strings and $ref both reference the registry; see Registry keywords.

A string that is none of these forms is an error, not a read:

/v: not a pointer

valid: false
errors:
  - { descriptor: not a pointer, message: unrecognized string descriptor }

The diagnostic names the string, so a typo fails loudly instead of quietly mapping the wrong thing.