This Supplement provides technical information (rationale) for setting the resistibility requirements against lightning in [ITU-T K.45]. This information should be referred to in the case of revision of [ITU-T K.45]. The rationale described in this Supplement is mainly quoted from past contributions and other documents discussed in ITU-T SG5 at the stage of establishment and revision of [ITU-T K.45].

This is a living document in that the rational justifying any future changes in [ITU-T K.45] testing should be added to this Supplement.

This Supplement references the tables, test numbers and test conditions found in [ITU-T K.45]. Rational information for the [ITU-T K.45] test values originates from various events, surveys, standards and ITU-T SG5 contributions.