MIT/GNU Scheme internally uses ISO-8859-1 codes for I/O, and stores character objects in a fashion that makes it convenient to convert between ISO-8859-1 codes and characters. Also, character strings are implemented as byte vectors whose elements are ISO-8859-1 codes; these codes are converted to character objects when accessed. For these reasons it is sometimes desirable to be able to convert between ISO-8859-1 codes and characters.
Not all characters can be represented as ISO-8859-1 codes. A character that has an equivalent ISO-8859-1 representation is called an ISO-8859-1 character.
For historical reasons, the procedures that manipulate ISO-8859-1 characters use the word “ASCII” rather than “ISO-8859-1”.
Returns the ISO-8859-1 code for char if char has an ISO-8859-1 representation; otherwise returns
In the current implementation, the characters that satisfy this predicate are those in which the bucky bits are turned off, and for which the character code is less than 256.