https://www.bailii.org/ew/cases/EWHC/QB/2019/3408.html
3. I have therefore included technical detail about the Horizon system, its operation, and some aspects of the technical evidence, in a Technical Appendix to this judgment. The contents of that appendix should not be seen as being of subordinate effect to the contents of the judgment itself; this is done simply for the convenience of readers. It is also intended that readers who do need to immerse themselves in technical matters to a very fine level of detail may not find it necessary to study the appendix, and reading the judgment alone may be sufficient. Notwithstanding that approach, however, this judgment too is extremely long. This is due to the complexity of the Horizon system, which even for computer systems is extraordinarily complicated for the reasons explained below; the period of time over which the complaints range (which starts with the introduction of Horizon in 2000 and runs to date); and due to the way that the litigation has unfolded. There are some matters in this judgment that go to issues affecting the group litigation going forwards, such as disclosure, which have increased its length. It is also the case that this litigation is being very strongly contested on both sides. I have endeavoured to provide a reasonable level of detail to explain my findings on the Horizon Issues to assist both sides as much as possible. Finally, the only findings that are made in this judgment are those necessary to come to conclusions on the Horizon Issues. All other matters in all the claims of the claimants and the counterclaims by the Post Office remain for decision in later judgments.