Part 6: Bulk warrants Chapter 1: Bulk interception warrants Section 137: Obtaining secondary data
This section describes secondary data which can be obtained under a bulk interception warrant. Secondary data means systems data or identifying data associated with or attached to the communications being transmitted. In order to be secondary data, identifying data must be capable of being separated from the communication in such a way that, when separated, it would not reveal the meaning (if any) of the content of the communication.
	Systems data is defined in section 263 as data which enables or otherwise facilitates, or identifies or describes anything connected with enabling or facilitating, the functioning of any postal service, telecommunications system or any telecommunications service provided by means of that system. Anything that is systems data is not content.
	Identifying data is defined in section 263 as data which can identify, or assist in identifying, any person, apparatus, telecommunication system or telecommunications service, or which identifies an event, or may be used to identify the location of any person, event or thing.
	Secondary data obtained under a bulk interception warrant will be subject to the relevant safeguards set out in Chapter 1 of Part 6.
	Secondary data could include:
messages sent between items of network infrastructure to enable the system to manage the flow of communications;
router configurations or firewall configurations;
software operating system (including the version of that system);
the period of time a router has been active on a network;
the location of a meeting in a calendar appointment;
photograph information - such as the time/date and location it was taken; and
contact 'mailto' addresses within a webpage.