A value that uniquely identifies the vCard.Namespace: vCards
Assembly: ICalVCard (in ICalVCard.dll) Version: 220.127.116.11 (18.104.22.168)
This value is optional. The string must be any string that can be used to uniquely identify the vCard. The usage of the field is determined by the software. Typical possibilities for a unique string include a URL, a GUID, or an LDAP directory path. However, there is no particular standard dictated by the vCard specification.