SWI-Prolog 9.2.9 Reference Manual: Section 4.26

## 4.26 Character Conversion

Although I wouldn't really know why you would like to use these features, they are provided for ISO compliance.

[ISO]char_conversion(+CharIn, +CharOut)
  Define that term input (see read_term/3) maps each character read as CharIn to the character CharOut. Character conversion is only executed if the Prolog flag char_conversion is set to `true` and not inside quoted atoms or strings. The initial table maps each character onto itself. See also current_char_conversion/2.
[ISO]current_char_conversion(?CharIn, ?CharOut)
  Queries the current character conversion table. See char_conversion/2 for details.