The lightning data collected by Lightning Locating Systems (LLS) operating in the Low Frequency range is of great interest in many end user applications. Because this data is derived from remote sensing measurements it suffers from inaccuracies depending on system technology and the effectiveness of the operations.

To guarantee the reliability and homogeneity of the various lightning datasets made available on the market, the IEC 62858 standard requires a minimum level of performance for an LLS to be qualified and deliver reliable data.

This document reviews the main performance parameters, the minimum requirements that must be achieved. It is defined by an LLS and introduce the lightning data structure and its relations with the natural lightning related electrical processes.

The objective of this paper is to give end users that are not knowledgeable on LLS some information about the limitations of LLS and the different data that are made available.