Unknown tag 0x89ab in IFD0

[ScannerBoy]

Recently, as part of my scanning some of my old film strips using the app Silverfast Studio, I have come across the warning:
Warning: Unknown field with tag 35243 (0x89ab) encountered (in module "TIFFReadDirectory")

As it turns out, that tag seems to be part of the private tag range for TIFF files according to the TIFF spec from: https://www.itu.int/itudoc/itu-t/com16/tiff-fx/docs/tiff6.pdf#page=8

Private Fields and Values
An organization might wish to store information meaningful to only that organi-
zation in a TIFF file. Tags numbered 32768 or higher, sometimes called private
tags, are reserved for that purpose

.

hence it might be better to reword the warning???

SG Edit: linked to exact PDF page

[Phil Harvey]

That is not a warning from ExifTool.

Sounds more like a warning from LibTIFF.

- Phil

[ScannerBoy]

Thank you, Phil
That is good to know.
Initially I expected the tag to show somewhere, but I now realize I need to use one of the -u/U options for that.

Since this specific tag is part of a recognized - ie legitimate range - is there a way to identify it as such?
As part of the description with the -u/U option?
After all, its purpose is sort of 'known' and it does appear in 'reasonable spot :-)

[StarGeek]

After all, its purpose is sort of 'known' and it does appear in 'reasonable spot :-)

But it isn't known. Different organizations might use it for different, conflicting, purposes.

If needed, you could always create a user-defined tag to cover it (see the Example Config file).

[ScannerBoy]

Agreed, not everything is known, except that it is part of a range of private tags, and, IMO, even that bit of information is better than nothing at all :-)
The standard does recommend that companies who use these  tags register them with a central authority, but thus far I have been unable to confirm that Silverfast has done so.
Then, again, if they don't there is nothing we can do, except record all we do know. ;-)

[ScannerBoy]

More searching gave me another bit of peculiar information
in https://exiftool.org/forum/index.php?topic=4790.0
the OP gave a small TIFF file he had issues with, also produced by an earlier version of Silverfast.
What is interesting, is that that file also uses the same tag, but with a different format - at least the data size is different
See the attached screenshots

[Phil Harvey]

There is also this post about tag 0x8470.

- Phil