Certification Authority ID definition
An ID that uniquely identifies the advertising system within a certification authority (this ID maps to the entity listed in field #1). A current certification authority is the Trustworthy Accountability Group (aka TAG), and the TAGID would be included here [11]. Declaration of certification IDs are superseded by the identifiers object in sellers.json. Note: This field belongs to 1.1 version and may be deprecated in future releases.