99.Section 21 amends section 19 of the Prisons (Scotland) Act 1989.(66) Under that section, the Scottish Ministers have a duty to provide young offenders institutions – places where offenders sentenced to detention in a young offenders institution, and those aged at least 14 but under 21 who are remanded in custody for trial or while awaiting sentence, can be held. As a result of amendments made to the 1995 Act by sections 18 and 19, no one under 18 will now be held in a young offenders institution. Section 21 amends section 19 of the 1989 Act so that young offenders institutions are defined as places for the detention of those aged 18 but under 21. Section 21 also amends the Prisons and Young Offenders Institutions (Scotland) Rules 2011,(67) which defines “young offender” to mean a person aged at least 16 but under 21 so that that expression will now mean a person aged at least 18 but under 21.