Edit ZIM metadata "in-place"

[benoit74]

While ZIM metadata are supposed to be right from the beginning, we regularly face situations where the ZIM produced is ok in term of content, but we have few metadata to edit.

Currently, the process we use consists in recreating the whole ZIM with one-to-one copy of most content and some modified metadata. This is both not very convenient and not

What are the possibilities to edit metadata in-place? If not possible to directly change them since their length might change, wouldn't it be possible to just leave old blobs as they are, create new blobs with updated metadata and update the pointers (TitlePtr?) to the new blobs? This means few bytes will be wasted, but since metadata are very small this would be only very marginally noticeable.