Write file content data

[ajk]

Every file can have a blueprint right? So even for pdf files its possible to write a blueprint with fields to store some extra data - right?

If yes: In the panel read and write is not a problem.
Read in the frontend / templates is also not a prloblem with $file->fieldname(); or $file->content()->fieldname();

But how do I write?

[texnixe]

You mean write to a file from the frontend or programmatically? Then $file->update() is what you are looking for:

$file->update()

[ajk]

That simple!