Where can I see the description of types and schema key:value?

Hi @ecarriou,

I learn how to use System Designer to design the database and relationship between forms.
And I got confused by the various options for types and schema key:value.
Where can I get a description of each options?
From there I hope to be able to understand more about how to use System Designer.
Or if there are more example of how the things work.

Example of things I want to do:
- in the forms there will be dropdown list of related items. How to create this dynamic list?
- also a dropdown but for a fixed selection like gender, how to make this?
- for a selection of location, I want user to select a city, then the system will auto-fill the state. How to relate state with city?
- etc.

Thank you
- System Designer version number: *v5.2.0*
- System Designer platform: *macOS*
- Your OS version: *macOS 12.3.1*

The issue mentions no files or tests; start by locating the existing documentation and examples for types and schema key:value options in System Designer v5.2.0. Document the available options and explain the requested related-item, fixed-selection, and city-to-state workflows, with examples showing how users can verify each result.

Written by the indexing model from the issue text.