1.1 General This International Standard establishes guidelines for ensuring the fidelity and security of pulsed data cabled transmission systems utilized for the metering of fluids (see the note), a main objective being to ensure the integrity of the primary indication (see 2.2.5). NOTE — Compliance with the requirements of this International Stan-dard does not increase the basic precision of measurement, either in the electrical or electronic section of the system, or in the overall system which includes the meter(s). 1.2 Levels of security 1.2.1 In order to achieve different levels of security (see the note and clause 3) which can be applied to such systems, criteria and recommendations for the design, installation, use and maintenance of the relevant equipment are laid down. NOTE— The levels of security are designated E to A, from the lowest to the highest order of security respectively. For the majority of applications, the lower levels are considered to be adequate and at the time of the publication of this International Stan-dard, there is no known system for which Level A security is con-sidered to be a necessity. 1.2.2 This International Standard does not define which levels of security are to be used for a particular system application. 1.3 Safety and regulatory requirements 1.3.1 Regulatory requirements, including those for safety, are not specifically covered in detail but certain general cautionary notes on safety are included for guidance (see the note). NOTE— Compliance with this International Standard in no way absolves manufacturers and users of systems and equipment from meeting all relevant legal metrology (weights and measures), safety and other regulations applicable in the country in which it is intended to use a system. Special attention is drawn to 0.5 and 0.6 of the Introduction.