...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
True if nulls are not allowed.
bool disallow_null = false;
Normally all possible character values (from 0 to 255) are allowed, with reserved characters being replaced with escapes upon encoding. When this option is true, attempting to decode a null will result in an error.