24 Ranges library [ranges]

24.7 Range adaptors [range.adaptors]

24.7.11 Split view [range.split]

24.7.11.6 views​::​split [range.split.adaptor]

The name views​::​split denotes a range adaptor object ([range.adaptor.object]).
For some subexpressions E and F, the expression views​::​split(E, F) is expression-equivalent to split_­view{E, F}.