[theducks]

Originally Posted by Odessa

I must say I'm a bit disappointed.

If anyone is able to answer this simple question : in what situations should one choose to embed metadata, and when is it advisable not to do so, I'd be grateful.

I would not expect you to embed your identifying metadata data if you plagiarized the work Calibre does insert custom column data (and posible values) into the OPF, so you might consider what those contain.
This is the Gunning fog entry from count pages plugin:

Spoiler:

<meta name="calibre:user_metadata:#fog" content="{&quot;is_csp&quot;: false, &quot;category_sort&quot;: &quot;value&quot;, &quot;name&quot;: &quot;G Fog&quot;, &quot;rec_index&quot;: 24, &quot;#extra#&quot;: null, &quot;column&quot;: &quot;value&quot;, &quot;label&quot;: &quot;fog&quot;, &quot;link_column&quot;: &quot;value&quot;, &quot;display&quot;: {&quot;number_format&quot;: &quot;{0:.1f}&quot;}, &quot;is_editable&quot;: true, &quot;is_custom&quot;: true, &quot;table&quot;: &quot;custom_column_5&quot;, &quot;is_category&quot;: false, &quot;search_terms&quot;: [&quot;#fog&quot;], &quot;is_multiple2&quot;: {}, &quot;is_multiple&quot;: null, &quot;colnum&quot;: 5, &quot;kind&quot;: &quot;field&quot;, &quot;#value#&quot;: 7.007464127878575, &quot;datatype&quot;: &quot;float&quot;}"/>

Metadata is that old card catalog set of cards, simply in a standard form that devices can read EASILY (most of that already appears on the Copyright and L C registration 'print pages.