A plot style table is a collection of plot styles assigned to a layout or to the Model tab. There are two types of plot style tables: color-dependent plot style tables and named plot style tables.
Color-dependent plot style tables (CTB) use an object's color to determine characteristics such as lineweight. Every red object in a drawing is plotted the same way. While you can edit plot styles in a color-dependent plot style table, you cannot add or delete plot styles. There are 256 plot styles in a color-dependent plot style table, one for each color.
Named plot style tables (STB) contain user-defined plot styles. When you use a named plot style table, objects that have the same color may be plotted differently, based on the plot style assigned to the object. A named plot style table can contain as many or as few plot styles as required. Named plot styles can be assigned to objects or layers, just like any other property.
You can use the Plot Style Manager to add, delete, rename, copy, and edit plot style tables. Both color-dependent and named plot style tables are stored in the Plot Styles folder by default.