Document, Range, or Selection object: Returns a Fields collection that represents all the fields in the document, range, or selection. Read-only.
Note When applied to the Document object, the Fields property returns a Fields collection that contains only the fields in the main text story.
MailMerge object: Returns a MailMergeFields collection that represents all the mail merge related fields in the specified document. Read-only.
For information about returning a single member of a collection, see Returning an Object from a Collection.