JEITA CP-3451
- 28 -
UserComment
A tag for Exif users to write keywords or comments on the image besides those in ImageDescription, and without
the character code limitations of the ImageDescription tag.
Tag
=
37510 (9286.H)
Type
=
UNDEFINED
Count
=
Any
Default
=
none
The character code used in the UserComment tag is identified based on an ID code in a fixed 8-byte area at the
start of the tag data area. The unused portion of the area is padded with NULL ("00.H"). ID codes are assigned by
means of registration. The designation method and references for each character code are given in Table 6 . The
value of Count N is determined based on the 8 bytes in the character code area and the number of bytes in the
user comment part. Since the TYPE is not ASCII, NULL termination is not necessary (see Figure 9).
Table 6 Character Codes and their Designation
Character Code
Code Designation (8 Bytes)
References
ASCII
41.H, 53.H, 43.H, 49.H, 49.H, 00.H, 00.H, 00.H
ITU-T T.50 IA5
JIS
4A.H, 49.H, 53.H, 00.H, 00.H, 00.H, 00.H, 00.H
JIS X208-1990
Unicode
55.H, 4E.H, 49.H, 43.H, 4F.H, 44.H, 45.H, 00.H
Unicode Standard
Undefined
00.H, 00.H, 00.H, 00.H, 00.H, 00.H, 00.H, 00.H
Undefined
Figure 9 User Comment Tag
The ID code for the UserComment area may be a Defined code such as JIS or ASCII, or may be Undefined. The
Undefined name is UndefinedText, and the ID code is filled with 8 bytes of all "NULL" ("00.H"). An Exif reader that
reads the UserComment tag shall have a function for determining the ID code. This function is not required in Exif
readers that do not use the UserComment tag (see Table 7).
ExifVersion
..
..
Exif Private Tag
Exif IFD
Value of
Exif IFD
Character Code (8 Byte)
..
User Comment Column
..
UserComment