Pips are distinguished by colour, and completed ribbons are highlighted in that colour. Incomplete ribbons are pastel shades.
As default, but ribbons are highlighted when they contain only a single colour, even if you still need to link them together.
Pips are distinguished by number and shade of red. Incomplete ribbons are shades of blue. Complete ribbons are highlighted in shades of red.
Pips are distinguished by shape. Completed ribbons have a dashed line along them with smaller copies of the pip shape placed along them.