It should be read in conjunction with Level 1, No. 21 How to avoid torsion, which provides an introduction to torsion and discusses how it can be avoided.
This is the first ‘Level 3’ note in the Technical Guidance Note series. Level 3 will cover more complex topics that assume greater prior knowledge on the part of the reader. As a rough guide, each Level 3 note assumes the reader is fully conversant with any relevant Level 1 and 2 notes that precede it.