Currently, we can classify and find characters by:
- category (central, minor, we can add others at same level, but a character can be in only one of them)
- gender (male, female, we can add others, but a character can also be on one only)

However, these two categories would not apply with "non human" species, and even in our world, we could prefer some other classification...

- species (with information about that species: origin, characteristics, language, history, links between species, etc...). Think about the Lord of the Rings.
- origin, family, guild, politics, etc... Think about Dune.

Maybe the best way would be to extend the categories, so that any could be created, with its own characteristics.
Gender and importance being only 2 (optional) between many (and then could even be removed if not suitable).

A character could then be part of many categories, not only 2 as today.

Example. Character X could be:
- Family a
- Gender b
- Importance c
- Guild d1 and d2
- Species e
- Speaking languages f1, f2, f3
etc...

Each a, b, c, d, e etc... are different categories, and we could find all characters from Guild d.
When creating a classification, we would create characteristics for it.
In any case, a character could be classified in as many categories as necessary, nothing being exclusive.

Does it make sense ?

Did you look at the Attributes? I think you can use this for your purpose. Don't forget to check the Attributes table and List of attributes.

I did indeed.

However, attributes are different from the 2 basic categories...

Or I don't know how to manage them.

Let say:

My world has no gender, but 2 categories are important:
- color
  can be red or blue only (non exclusive - character can be one or both or none)
- species
  can be bird or bug only (exclusive)

When I create a character, after the database is setup, gender should be replaced by my 2 attributes, and left pane should let me find them (list character by color, and species) and forget about gender.

Current attributes looks like more a criteria (being red) rather than being in a category "color" with value "red".
In that sense, being "male" or "female" would not be part of "gender", but just a name (it is different in current version, gender can include different values, but a new category "color" cannot be created with the 2 possible values "red" and "blue").

Maybe I missed something, I did not play enough with the software

If I understood correctly, what you would like is a particular categorization (name and description) having the possibility of multiple association for one character, somehow a reverse Relationship.

There may be - for the moment - only two different categorization systems. However, under ech categorization, you may create as many new categories and even sub-levels recursively (I also have several genders in a project).I have just tested that and it seems to work, with one limitation : there is no verification of possible loops. For example: you create a category named "bug", under which you put a "red" sub-category. You may then change the "bug" category to put it under the "red" category. This will crash your database with the current version. I have done it during my tests.... I already have prepared a protection against the crash, not yet to prevent doing the loop.As far as I know, we haven't yet planned to extend the number of trees (only the existing two are defined).Nevertheless, allowing several categories for a character may be a very good idea.

Exact.

Gender should be considered as just a category/attribute example (and could be removed).

Color or species etc... could be different attributes, with different possible values (exclusive or not).
Each attribute would have a description, as well as each possible value.

Oops, I missed your last post.

Yes, ideally, an attribute could link to another attribute (like gender is only for human and dwarves, but not for snails), but I am afraid it would quickly become a full graph instead of atop-down tree.

Not so important.

So I just come back to the point:
- the 2 existing attributes should be given as examples
- we should be able to give more than 1 value for 1 attribute (i.e. Male or Female or both or none).
- the left pane should show the existing attributes in project, not the 2 given examples