Hello!
According to this guide - Integrations File System Reference – Shotgun Support - there is a way to utilize so called “optional” fields. But how? The example creates a folder with an optional field in use. If I try to utilize syntax with “” nothing works. Are there any in-depth guides on this topic, or any further information. The documentation is more confusing, than helping 
Best regards,
Dietmar
Optional fields work fine for filenames, but I wonder how they’d work for folders, given that they have to conform to your folder schema. You may have to provide branching paths (e.g. one with and one without the optional field) in your folder schema.
Someone with more experience in this should chime in.
Could you explain a bit more about “nothing works”? Were there errors?
That’s the point. At the tutorial they demonstrate the behaiviour on a folder, but for me it works only for files. Not folders. Shotgun DEVs, please tell us which way! 
I see, then probably your folder schema has to accommodate all possibilities with optional components, e.g. you need both
project/shot/task
and
project/task
as possible paths in the schema.
So what’s the folder-name syntax. Assuming I want to use a folder structure like:
…/globalAssets/[asset.parent]/asset/and-so-forth/and-so-on/…
Brackets are not allowed. Dot-syntax - no idea, didn’t tested it yet 
For the templates square brackets should work… but the schema is a folder structure which defines how the hierarchy will be created. So that has to match the templates, including possible branching.