CG50224 - Capital Gains Manual - HMRC internal manual
The definition of relevant security is in TCGA92/S108. Full details are in CG51150-51151. Relevant securities have their own identification rules, see CG51153+. These rules apply for all persons up to 5 April 1998. For disposals on or after 6 April 1998 the rules apply only for companies and other concerns within the charge to Corporation Tax; for disposals by others, eg individuals within the charge to Capital Gains Tax, the normal share identification rules apply, see CG51140.