PVA is polyvinyl alcohol and B72 an acryloid.  Know the
chemical reactivity, solubility etc.  suggest you
consult with Conservator on labelling.
Clear nail polish under, number nail polish over has
been used in registration.  We careful where and on
what it is used on.  White out sometime used.
On fabrics a tab of twill tape with number carefully
sewn on.  Conservator will advise.
        sharon, conservator speciality textiles