(9) SI engines exclusively for use in snowmobiles. ‘category SMB’: Engines for snowmobiles other than SI engines are included in the category NRE; (10) SI engines exclusively for use in all terrain and side-by-side vehicles ‘category ATS’: (ATVs and SbS). Engines for ATVs and SbS other than SI engines are included in the category NRE. 2. A variable-speed engine of a particular category may be used in place of a constant-speed engine of the same category. Variable-speed engines of category IWP used constant-speed for shall additionally comply with Article 23(7) or Article 23(8), as applicable. operation 3. Engines for auxiliary railway vehicles and auxiliary engines for railcars and locomotives are included in the categories NRE or NRS, according to their characteristics.
(9) ‘category SMB’: SI engines exclusively for use in snowmobiles. Engines for snowmobiles other than SI engines are included in the category NRE; (10) ‘category ATS’: SI engines exclusively for use in all terrain and side-by-side vehicles (ATVs and SbS). Engines for ATVs and SbS other than SI engines are included in the category NRE. 2. A variable-speed engine of a particular category may be used in place of a constant-speed engine of the same category. Variable-speed engines of category IWP used for constant-speed operation shall additionally comply with Article 23(7) or Article 23(8), as applicable. 3. Engines for auxiliary railway vehicles and auxiliary engines for railcars and locomotives are included in the categories NRE or NRS, according to their characteristics.