simple reshade install question

During reshade setup, i am presented with a screen 'Select effect packages to install'
The effects with a checkbox in front of them are listed.
The checkbox has three states.
blank
solid
checked

I assume blank means the effect is not installed and the checkmark means that it is installed.
What is the solid box for?

Blank = Skip downloading/installation of that package
Solid = Download the package and ask which effect files that are in that package to install in a follow up step
Checked = Download the package and install all effect files in that package

thank you