A list of additional files or directories that are associated with the
primary file and must be transferred alongside the primary file.
Examples include indexes of the primary file, or external references
which must be included when loading primary document. A file object
listed in secondaryFiles may itself include secondaryFiles for
which the same rules apply.
A list of additional files or directories that are associated with the primary file and must be transferred alongside the primary file. Examples include indexes of the primary file, or external references which must be included when loading primary document. A file object listed in secondaryFiles may itself include secondaryFiles for which the same rules apply.