CHARACTER_REF

Used .NET classes

Static methods used

Security notes

Unhandled exceptions

Other notes

Had to add/change preconditions in Base, because Base is ASCII and Base.NET is Unicode.
Added is_valid_character_code in INTEGER_REF for this purpose.
Also added min_value/max_value in CHARACTER_REF (0-255 for Base, 0-65535 for Base.NET).