Various shades of blue have been used in the saltire over the years. The ground of the current Union Flag is a deep "navy" blue (Pantone 280), which can be traced to the colour used for the Blue Ensign of the Royal Navy's historic "Blue Squadron". (Dark shades of colour were used on maritime flags on the basis of durability.) In 2003 a committee of the Scottish Parliament recommended that the flag of Scotland use a lighter "royal" blue (Pantone 300) (the Office of the Lord Lyon does not detail specific shades of colour for use in heraldry).