Polyvinyl alcohol although sometimes referred as PVA, often confused with Polyvinyl acetate PVA. Using PVOH for short is better imo.
As far as I know, few of the pt/pd printers use PVOH as a thickener for emulsion.
Adding concentrated PVOH makes the pt/pd sensitizer more viscous and easy to apply to very absorbent thin papers like washi and gampi.