From OpenStreetMap Wiki
- "Grouping of closely related keys in namespaces helps to separate this group of keys", see Namespace. (intention of splitting the services up within motorcycle:*=*)
- "avoid ';' separated values whenever possible", see Semi-colon_value_separator
i.e. (motorcycle:type=standard;dualsport;chopper;sportbike) is not the ideal way to tag shops which sell every type exept scooters.
(Unless you're currently forced to to similar stuff with brand=KTM;BMW;Honda;Yamaha;Suzuki...)