There are 661 small text files used to describe the Summit calendars. These are generated from the output of a DePfa Summit utility cdatrep.
The interface is
This returns a JointCalendar of two BespokeCalendar objects. The cal.name() is then
QuantLib::Calendar::JoinHolidays(EUR, LON)
The Summit calendar called LPB is this one.
QuantLib::Calendar::JoinHolidays(JoinHolidays(JoinHolidays(JoinHolidays(JoinHolidays(BRU, DUB), EUR), LON), LUX), PAR)