NFD » ndn-cxx

They should be equivalent to the operators in std::literals::chrono_literals, except that the literal suffix identifiers must start with an underscore character, as required by the C++ standard:

[usrlit.suffix]

1. Literal suffix identifiers that do not start with an underscore are reserved for future standardization.

Unfortunately we cannot use the standard chrono_literals directly because they would return an std::chrono::duration, which is incompatible with ndn::time::duration.