How do Now button variables work?

When an action field has the option to insert variables with {…} at the bottom, I see that Now buttons appear in the list of options. I was aware that Connectors have a persistent variable value, but I was not aware that Now buttons have a value. When I test it, the result is that the value of all Now buttons is “pushed”, even those that were not pushed to activate this Trigg. Is there supposed to be a different result? Is there an intended use for Now button values in this context?
I guess from the “{…}” that this may be inserting some form of JSON, although it shows up as a human readable graphic label. There is a switch on the variable selection screen that is labeled “Human readable”, on by default. But whether that switch is on or off, the variable appears in the same human readable format. Is the switch supposed to have some effect?