I haven't fully explored the differences in the largely undocumented formatting options for style properties and XF options.
I don't know if documentation has improved, but I am trying to find out if there is anything that will specify a default value if I am creating an addon.
My problem happens when creating a new field in style properties--specifically, Typography. In "Value formatting parameters," I can specify something like min=100 and max=900 but since the master style automatically assigns a "0" value, it throws an error when testing the new style property fields in a style I am modifying (not the master style), saying the value needs to be between 100 and 900 before I can save the style properties page (such as, Typography).
So there seems to be no "default=" option that I can tell (tried it, it didn't work). Similar fields use what is shown in the master style. Sure, I can change the "zero" values to something arbitrary, but I don't see that number entered into the master style (whose data we should
never alter) having the ability to be saved to an addon.
It's a little hacky to remove the "min=" definition, but it does let a person continue without having to fill in values to correct the errors. (In my use case, values below the minimum aren't invalid and won't throw errors...but they also won't have any effect on the outcome. In other words, anything less than 100 is treated as 100. Hence, hacky.)
If these "Value formatting parameters" were documented, it would certainly help.