If DITA2Go fails to find a definition for an assigned format component name in the current format component template file, DITA2Go looks for the definition in any configuration files assigned in [Templates] to Formats, Tables, Pages, and Subformats, in that order.
For example, if a border format is based, DITA2Go looks for the base definition using the same process, but starting with the file that contains the sought format component definition, not the original file. For example:
[MyPara] border bottom = MyBorder
[OtherBorder] color = blue
[MyBorder] based = OtherBorder
[OtherBorder] color = red
The border under each MyPara paragraph will be red, not blue.