nearly there, page-4

oilleak:

PU Protection unavailable
PU is displayed for a security when the underlying security commences trading on an Ex basis of quotation and remains until the close of business on the applications close date. Protection Unavailable is a warning to Optionholders that if they exercise their option during the underlying security's Ex period they will not receive the entitlement associated with the underlying security. All orders are purged at the end of the trading day prior to the security being quoted on a PU basis.