vEvent.OptionalUnique

the following are optional, but MUST NOT occur more than once

struct vEvent
enum OptionalUnique = ["CLASS", "CREATED", "DESCRIPTION", "DTSTART", "GEO", "LAST-MOD", "LOCATION", "ORGANIZER", "PRIORITY", "DTSTAMP", "SEQ", "STATUS", "SUMMARY", "TRANSP", "UID", "URL", "RECURID", "SEQUENCE"];

Meta