You need to write
The first and last double quote mark the beginning and end of the string, the backslash is the C-style escape character that tells the compiler to treat the following character differently (in this case insert the double quote instead of terminating the string literal).
Is there a method for asking for specific character 0xF8 / 0xB0 (degree symbol) ?
the example letter.txt="\xF8" gives a 0x20 0xFF 0xFF 0xFF Improper use of escape characters.
Selective Escape at best :) Still fighting with it.
Though a partial escape sequence has been implemented in current versions
The \xF0 sequence will report a 0x20 Error code as improper use of escape sequences
The \xF0 sequence remains a Feature Request
This will now be marked as solved.