Method 15 for Host to TCP conversions
The method shown in Figure 67 has the following characteristics:
- It is used for conversion between an input Host CCSID and an output TCP CCSID.
- The valid encoding schemes for input data are X'1100', X'1200', and X'1301'. The valid output encoding scheme is X'5404'.
- Input is always expected in a normalized two-byte format.
- The conversion table created will handle either single-byte or double-byte code points from the input CS, CP pair to a possible single-byte, double-byte, or triple-byte output CS, CP code point as defined by the TCP encoding scheme.
- CS, CP pair priorities for the TCP CCSID
- Matched GCGID priority within a CS, CP pair
- Mismatch management criteria
- Space character management.
- Most double-byte encodings do not use all of the available first bytes as valid ward numbers. To handle this situation and make effective use of table resource space, the table is organized as a series of subtables. Each subtable contains 256 four-byte code point entries. There is a subtable of output code points for each valid ward number of the input code points, and a single subtable for the substitution entries for all of the invalid first-byte values.
- Invalid single-byte code points (X'00xx') will be mapped into the single-byte character SUB, at code point X'1A'.
- Invalid double-byte values will be mapped as follows:
- Japan - X'747E'
- Korea - X'2F7E
- Traditional Chinese - X'7D7E'
- Simplified Chinese - X'2121'(24)
- The high order byte of each output code point contains the identifier from 1 to 4 for graphic characters, or 0 for control characters.
- Host double-byte control characters will be mapped to single-byte control characters after denormalization.
Figure 67. Method 15: Host to TCP Conversion