Scoped

A value that a level either sets, or does not (config-ui §CFGM-4).

In the namespace config. Declared in src/libs/libconfig/config/Scoped.hpp.

Detailed description

"Unset" is a state, never a sentinel value. The tree paid for the sentinel form once: `ConstructViewportProducer::RenderOptions` spelled unset as `kUnsetF`, `-1` or an empty QString, until `tracerId` needed to tell null (nobody asked) from empty (the "Auto" record).