A String is a sequence of char values in UTF-16, and is seen in C# (which Resonite is written in). A String is considered an object not a value internally and when choosing the difference between an object or a value, it is an object. In the case of choosing between only either a reference or a value, it is under value.
A String can be made in ProtoFlux by concatenating different Strings together, or by concatenating 2 or more char objects together.
Note: If you are willing to handle "special characters" which requires "surrogate pairs" to express it in UTF-16, you may want to use String To UTF32 (ProtoFlux Node).