string source functionthat reads its argument
value string source, and returns the text of that data converted from a Shift JIS encoding to a UTF-8 encoding. That is, the provided source is in Shift JIS, but the program sees UTF-8.
string sink functionthat accepts UTF-8 encoded data and writes that data to its
value string sinkargument, converted from a UTF-8 encoding to a Shift JIS encoding. That is, the program writes UTF-8, but the provided output receives Shift JIS.
The data formats are interpreted/produced according to the Japanese Industry Standards JIS X 0201, JIS X 0208 and JIS X 0212. The Shift JIS data format is transformed using the JIS⟺Shift JIS conversion algorithms.
The only kinds of errors that can occur are in conversion: finding a character that does not have a conversion
in the other character set. In this case, the converted value use is
the Shift JIS encoding, and
0xFFFD) in the Unicode (UTF-8) encoding.
These functions are based on  Ken Lunde, “Understanding Japanese Information Processing”, O'Reilly 1993, ISBN 1-56592-043-0.
To use OMFFSJIS, you must import it into your program using an import declaration such as:
import "omffsjis.xmd" prefixed by sjis.