Event Token is a Unique Identification of the Event to identify each particular event conversion and needs  to be created by Advertiser or Network.
*Event Token supports  up to 32 characters of English letters, number,and characters "_", ".","-". The  conversion will be recorded as Pending if  The event token should be unique for each event in an offer). Once conversion is completed, if english letter cases are different, conversion will be recorded as pending.