Erasable Ink is ink that will rub off when an attempt is made to erase information in the area that has been printed.
The Erasable Ink will also have an affect on the paper in the same manner as solvent/chemical reactive inks do, giving you two security features in one. Often used to print the background of a check.
This feature is effective primarily in document-present situations where the original document can be examined by a trained professional or scanned with a specialized 3-illumination ID scanner and analyzed with adequate forgery detection technology.
Usability in online and mobile onboarding situations is challenging as the examination is made not on the physical document but on a photograph or scanned image of it.
Ref.: https://www.gpo.gov/pdfs/customers/security_glossary.pdf