http://fadyart.com/financeV4#MandatoryOptionalCorporateAction
Class MandatoryOptionalCorporateAction

owl:Class

For optional mandatory corporate actions, the holder of the securities can take no decision on the corporate action happening but he has the option to choose between modalities. E.g. optional dividend: cash or stock.

http://fadyart.com/Finance/v3.04

Mandatory optional corporate action

Standing instruction for corporate actions

VoluntaryCorporateAction