Json format - char exceptions

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C++

I'm writing some routin to manage files in Json format.
the file format specified on www.json.org is very clear... but I cant relly get the mean of the exceptions on 'chars' type.
There is written:

char
    any-Unicode-character-
        except-"-or-\-or-
        control-character
    \"
    \\
    \/
    \b
    \f
    \n
    \r
    \t
    \u four-hex-digits

I'm not understanding 2 lines.
In C++ looks that the chars \f and \u are not included. (Any way to have a understandable print-out on console)
What are their mean??