Thank you for this quick and useful answer.
It works, as it appears in MetaData panel in Bridge, to well understand I have modified the properties.xml file from Generic and put it in .../custom folder.
But now when I use file info in Bridge, only tab with label name is shown.
The problem is "manifest.xml", located in Custom File Info Panels / 4.0 / panels / Generic, looks for "properties.xml" which is located now in Custom File Info Panels / 4.0 / custom
I think this line must be changed to target to right location :
propertyDescriptionFile = "properties.xml"
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I haven't find any information about targeting syntax...
Can you help me again ?