A string value
that represents the type of changes that an end user can perform
on a PDF document without invalidating the certification signature.
It is used in the Certify PDF operation operation of the Signature service. These string values
are valid:
FormChanges:
The end user is permitted to fill in the form, instantiate
page templates, and sign the form.
AnnotationFormChanges:
The end user is permitted to fill in the form, instantiate
page templates, sign the form, and create annotations, deletions,
and modifications.
NoChanges:
The end user is not permitted to change the form. Any change invalidates
the signature.
