The points scoring system changes according to national series.

After the 2011 season, Burton desired to move up to full-time competition in a national series.

These websites were successful, even after some national series began charging for access to the video stream.

Rock crawling competitions range from local events to national series.

The club was since absorbed into the D1 franchise as a national series.

The cars began to compete regularly in 1998 with the formation of a national series.

In the late 1990s a single national series emerged as the primary venue for the cars.

That was a great "news hook," as we say in the newsroom, for our big national series.

The race grew from a small single event in 1972 into a national series with the sponsorship.