Understanding question regarding "metadata keeps reappearing"

[axel.hennig]

I would like to better understnad metadata-tags mapped to other metadata-tags.

I was reading this post started by Thorsten with the following comment

Similar to the "My metadata keeps reappearing" topics popping up again and again.

I also had this "reappearing metadata", but in most cases I know how to solve it.

Example: If I choose in a newly created database the Metadata-Layout "7 GPS Details" it has under "EXIF GPS" the tag "{File.MD.GPS::Main\0\GPSVersionID\0}". One of my testfiles has this tag filled with "2.3.0.0". If I delete this entry and write-back metadata it reappears. I think, because it gets refilled with what is in "{File.MD.XMP::exif\GPSVersionID\GPSVersionID\0}".

Question 1: Why is the tag "{File.MD.GPS::Main\0\GPSVersionID\0}" not marked as "This field is mapped to an XMP field and cannot be edited directly. Please update the corresponding XMP field instead".

My assumption would be if tag-A is mapped to tag-B and I change tag-A, then tag-B will be overwritten with what I put into tag-A and the other way round. But it seems like tag-A always overwrites (during write-back) tag-B, regardless if I update tag-A or tag-B.

Question 2: Would it be possible / make sense that additionally to the message "This field is mapped to an XMP field and..." it also shows to which field it is exactly mapped?

[Mario]

The GPS Details layout has been removed for IMatch 2023. If you don't import the new layouts, you'll keep existing layouts of course.

General rule: Do not manipulate native metadata (anything that's not XMP) in IMatch, unless absolutely required.
IMatch favors XMP (more and more). During write-back IMatch maps XMP data back to native metadata like EXIF, legacy IPTC and GPS. This will wipe changes done to native tags.

Re: Question 1: I have no idea. The idea to mark some tags as mapped is my thing, and I maintain these mappings by hand in a XML file shipped with IMatch. ExifTool has no machine-readable information about which tags are mapped. I figure this out by hand, looking at the ET config files, the documentation and doing tests.

It probably just did never occur to me that a user would manually set or change the value of the native GPS version id. I don't even know which values are valid for this tag.

Re: Question2: See Question 1. I need to add and maintain this information in the metadata configuration file, for each tag.
There are not many mapped tags if you use the layouts shipped with IMatch 2023, and the GPS Details is gone entirely.
I doubt enough users would be interesting in knowing such details. If somebody really needs to know that, he can look into the immbcfg.xml config file.

[axel.hennig]

Thanks for explaining.

I had a quick look into immbcfg.xml and maintaining this would drive me crazy. I had the (stupid) thinking that the mapping is done by Phil (and provided via ExifTool).