Difference between user categories and subgroups?

[CarstenF]

Hi all,

I'm quite new to calibre, and just found this page about subgroups in the documentation:
http://manual.calibre-ebook.com/sub_groups.html

This is exactly what I was looking for, but it seems to imply that hierarchies/subgroups are different from user categories ("A subgroup (e.g., a genre) must contain (point to) books, not categories of books. This is what distinguishes subgroups from calibre user categories.").

From the section about the Tag Browser at http://manual.calibre-ebook.com/gui.html#tag-browser however, I was not so sure: in this text, it seems that subgroups are just a synonym for user hierarchies. (The four-step filter cycle seems to have the same behavior for both, does it?)

Thus, is there any difference at all?
If so, what is it?

Many thanks and best regards,
Carsten

[eschwartz]

Correct.

Sub-groups == hierarchies == "tag.subtag"

User categories contain multiple tags -- or other metadata fields.

[CarstenF]

Hi eschwartz,

many thanks for your reply!

I'm sorry, but I need a bit more clarification: With "correct", did you mean:

• "correct, they are all synonyms", or
• "correct, they are totally different from each other" ?

Starting with your answer, I also re-read the docs pages mentioned above, and was thinking more about it...

... would you say it is right that sub-groups (hierarchies) are quite like plain tags, with the exception that their tag names have a special structure ("the.dot.for.hierarchy.levels") and are (thus) specially presented (namely hierarchically in the Tag Browser)?

... and that a user category and each user sub-category can have its own, independent set of tags (possibly presented as.a.hierarchy)?

(Btw., are all types of metadata "a kind of" tag?)

Thanks,
Carsten

[eschwartz]

Correct, they are synonyms.


sub-groups (hierarchies) are plain tags. The difference is that calibre knows how to split them hierarchically along the "." in order to display them in the tag browser view.
This is an aspect of the tag itself.

In contrast, User Categories are a setting in calibre which groups certain tags or elements in various metadata fields together (it doesn't have to be the "tags" field).



Many (most) metadata fields are NOT tag-like, although they are displayed in the tag browser. Tags are a metadata field that contains a series of comma-delimited values.
"identifiers" does the same.
You can also create a tag-like custom column.

[chaley]

A user category can contain other metadata such as tags, authors, series, or what-have-you. For example, you could make a user category "Favorites" that contains your favorite authors, favorite series, and tags that indicate a book is a favorite.

A subgroup is simply a hierarchy in an existing category, such as a tag History.Military History. 20th Century. It exists only to make viewing the category easier. Turning it off and on does not change what the category contains, only how it is displayed.

[CarstenF]

Hi eschwartz, hi chaley,

ok, got it!

Many thanks for your help!



Best regards,
Carsten