"Modern C++ Features – User-Defined Literals"
http://arne-mertz.de/2016/10/modern-c-features-user-defined-literals/
"User-defined literals are a convenient feature added in C++11."
"C++ always had a number of built-in ways to write literals: Pieces of source code that have a specific type and value. They are part
of the basic building blocks of the language:"
Interesting.
Lynn