The number of crew members who can go over the wall during a pit stop next season has changed from six to five. The new requirement is part of the standardized at-track rosters NASCAR will use beginning in 2018. The details were announced Wednesday morning and detailed by NASCAR executive vice president and chief racing development officer Steve O’Donnell during a media teleconference.

What this means is that teams in all three NASCAR national series will have a standard number of individuals who can work on the cars each weekend. It will be at the team’s discretion how to make up its roster, which will be made public to fans and media before each weekend.

As part of the requirements, each roster member will also be assigned a number/letter based on his or her position and it will be required that it is visible at all times. Also new beginning next season is that the fueler will no longer be allowed to perform any other duties during a pit stop, such as making a chassis adjustment.

The rosters have three categories: Organizational, Road Crew and Pit Crew. Here’s a breakdown of how many members will be allowed per each category.

Organizational: Three for teams who are a one- and two-car operation. Four spots for those who are three- and four-car operations. This is where individuals such as the competition direction, team manager, technical director and IT specialists would slot in. In the Xfinity Series and Camping World Truck Series, they will be allowed one member.

Road Crew: 12 members for the Cup Series with seven in Xfinity and six in the Truck Series. This position is for crew chief, car chief, mechanics, engine tuners, engineers and other specialists, as well as the team’s spotter.

Pit Crew: It will be five crew members for teams in all three national series. of course, these are the individuals who perform over-the-wall duties during a race.

There will be slight exceptions to the road crew position as NASCAR will allow teams one extra person at Indianapolis Motor Speedway and the three road courses in the Cup Series, since a second spotter is often employed. In the Xfinity Series, teams will be allowed an extra road crew spot for 10 races while it will be five races for teams in the Truck Series.