New rule extends life cycle of a song.

Introducing digital data to the singles chart has one positive side- effect - it has helped slow down a countdown which had long been criticised for its relentless speed.

With the pattern of sales for a download typically spread over a longer period than for physical singles, hits have endured longer in recent months.

And the trend is likely to intensify, as sales will be counted earlier in a single's life cycle.

At the other end of a single's life cycle, big hits such as Gnarls Barkley's Crazy, Nelly Furtado's Maneater and Snow Patrol's Chasing Cars have fallen foul of a rule which dictates that any hit is automatically removed from the chart two weeks after being physically deleted.

Under the new rules, this will no longer happen, so extending a hit's chart life even further.

OCC chart director Omar Maskatiya suggests that this specific change could potentially slow down the countdown, with negative results. "From our point of view, the chart that we licence does need to be vibrant and does need to be exciting," he says.

"If it becomes too stagnant, everyone will want to look at it from a business perspective." The rules will be ...