Somebody understood the File-external Data Dialog? Please help!

I added textures from different directories which i do not all remember. So i packed them in the blend. I thought i could unpack them in an explicitly mentioned texture (collection set) directory, but no dice.
All it offers is some cryptic menu, which i do not understand. Looking in the Python API does not help, only method names are repeated but no explanation about used directories. What am i missing?

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I haven’t used this but as i understand it:

  • use in current dirrectory : if you already have your images in the current dirrectory
  • write into c.w.: if you want to export them now and use them in the future
  • use in original location: if you have the same enironment as in the original machine and don’ have to export them again
  • write o.l.: if you had deleted them in the o.l.

From time to time it may be a good idea to pack the images and save a biiiggg file to have them all gathered in one place… but then again saving again and again writes big files so maybe just use the locale file…