The Prototype Style for Characters
The Prototype style is the parent to all other styles. When you set a property for the Prototype character style, other character styles inherit the value of that property. You can then override that value for specific styles as needed. The Prototype character style allows you to quickly change a default property and apply that change to all character styles within your Stationery project.
Depending on how you organized your styles in Style Designer, you may not have one style as the parent style on which all others are based. The Prototype style ensures that each of your styles has a parent style within your Stationery project.