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  ## Field name resolution

  The document schema declares the vocabulary of known field names.  During
  preprocessing traversal, field name in the document which are not part of
  the schema vocabulary must be resolved to absolute URIs.  Under "strict"
  validation, it is an error for a document to include fields which are not
  part of the vocabulary and not resolvable to absolute URIs.  Fields names
  which are not part of the vocabulary are resolved using the following
  rules:

  * If a field name URI begins with a namespace prefix declared in the
  document context (`@context`) followed by a colon `:`, the prefix and
  colon must be replaced by the namespace declared in `@context`.

  * If there is a vocabulary term which maps to the URI of a resolved
  field, the field name must be replace with the vocabulary term.

  * If a field name URI is an absolute URI consisting of a scheme and path
  and is not part of the vocabulary, no processing occurs.

  Field name resolution is not relative.  It must not be affected by the
  base URI.

  ### Field name resolution example

  Given the following schema:

  ```
- $include: field_name_schema.yml
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  ```

  Process the following example:

  ```
- $include: field_name_src.yml
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  ```

  This becomes:

  ```
- $include: field_name_proc.yml
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  ```
