MacOS Big Sur has arrived and it has a new style for table views. This new style makes rows taller and also adds some space to each row, insetting them. While you may like your app to adopt this look for most of your tables, it is possible that some tables look odd when insetted. There is a new style attribute you can apply both in IB and in code, which by default is set to automatic.
NSTokenField is particularly tricky to use with Core Data bindings. I wanted to model a to-many relationship between an object (specifically Client, Project, etc.) and multiple Tags. The user would select e.g. a client from a table view, and in the inspector panel a token field would represent the assigned tags, which the user can edit. It’s a typical master-detail configuration. Tags that already exist are autocompleted; non-existent tags are created once the focus leaves the field.