SNOMED CT® Release Format 1 (RF1) Guide - ihtsdo

2.3.7.2.2.1. Single byte encoding
Characters in the range 'u+0000' to 'u+007f' are encoded as a single byte.
Table 23: UTF-8 Single Byte Encoding
2.3.7.2.2.2. Two byte encoding
0
byte 0
Characters in the range 'u+0080' to 'u+07ff' are encoded as two bytes.
Table 24: Two byte encoding
1
1
0
byte 0
2.3.7.2.2.3. Three byte encoding
bits 6-10
Characters in the range 'u+0800' to 'u+ffff' are encoded as three bytes:
Table 25: UTF-8 Three Byte Encoding
1
1
1
byte 0
bits 12-15
2.3.7.2.3. Notes on encoding rules
0
1
0
1
0
byte 1
bits 6-11
bits 0-6
1
byte 1
0
bits 0-5
byte 2
bits 0-5
The first bits of each byte indicate the role of the byte. A zero bit terminates this role information.Thus possible
byte values are:
Table 26: UTF-8 Encoding Rules
Bits
0???? ?? ?
10??? ?? ?
110?? ?? ?
1110? ?? ?
1111? ?? ?
Byte value
000-127
128-191
192-223
224-239
240-255
Role
Single byte encoding of a character
Continuation of a multi-byte encoding
First byte of a two byte character encoding
First byte of a three byte character encoding
Invalid in UTF-8
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