EXIF update error in TIFF file

[ooo.ooo]

XNViewMP 0.56 beta
View -> Details (with EXIF "Comment" column active)

1. Select JPG file(s), then press ^D (Set comment...)
2. Modify embedded comment and press [Write]
3. Comment is now correctly changed and updated
4. Press ^D again, modify Comment again, all OK, works fine in JPG files

1. Select TIFF file(s) and modify comment same as previous on JPG
2. Column "Comment" report NEW comment, but...
3. Press ^D again: old comment is displayed forever

See EXIFTools and XNViewMP Propertied tab for changes.
DNG files not investigated, but perhaps report same problem.

[xnview]

'Embedded comment' is only supported by JPEG currently...

[ooo.ooo]

IPTC is anyway considered "standard" field?
Can I use IPTC "Caption" and others fields?
TIA

[xnview]

IPTC is anyway considered "standard" field?
Can I use IPTC "Caption" and others fields?
TIA

IPTC works on TIFF/JPEG

[mahikeulbody]

IPTC is anyway considered "standard" field?
Can I use IPTC "Caption" and others fields?
TIA

Well, IPTC is not exactly the name of a standard, it is a name of the organisation (International Press Telecomunication Council) which manages the standard about press metadata (which include photo metadata). By extension, their previous standard was often called IPTC but the exact name was IPTC-IIM. But since a few years the new IPTC standard is IPTC-XMP based on XMP format (from Adobe) and IPTC-IIM is being (slowly) deprecaded. XnViewMP is able to manage both and, in most cases, to synchronize both but the IPTC recommendation is to use IPTC-XMP.