On Inauguration Day, more than 400 volunteers from Capitol Hill offices will pick up, deposit and re-collect 100 to 150 “packages” around Capitol Hill.

It sounds like a nightmare for the law enforcement officers who respond to every unattended parcel with utmost suspicion — especially during one of the highest-security events of the year.

But Grace Rooney, the Joint Congressional Committee on Inaugural Ceremonies escort and volunteer coordinator, explains the insider parlance: “Packages” are the groupings of VIPs attending President Barack Obama’s swearing-in ceremony on Jan. 21.

Supreme Court justices and Obama’s Cabinet are packages; so are members of Congress and former presidents and their spouses. Beyonce is a package, and so is James Taylor.

They don’t just arrive and negotiate their own seating arrangements, Rooney explained, nor do they leave the event without supervision. They don’t walk onto the Capitol grounds and over to their seats on the West Terrace platform in any uncharted route.

Every diplomat, dignitary and public official is greeted at specific entry points around the Capitol and accompanied by volunteer escorts to where he or she has to be. Volunteers have practiced their walking paths over and over again, with Rooney keeping track of what worked and what didn’t. With the inauguration’s success hinging on a precise schedule, she said, it’s essential to know everyone’s arrival times and modes of transportation.

Assigning walking routes for the VIPs is also important in anticipation of individual needs. Will an elderly guest need to enter the Capitol on a ramp? Did a Cabinet member sprain her ankle and now requires an elevator to get up to Statuary Hall?

With so many people moving simultaneously through the Capitol, specific routes also help keep the pedestrian traffic under control. Volunteers will also know which holding rooms will accommodate their VIPs while they wait to be escorted onto the inaugural platform.

The volunteers have worked hard for this, but on Jan. 21 it will be Rooney’s show. Stationed in a command center in the Capitol, she’ll be connected by radio and land line to her crew throughout the complex, troubleshooting from afar any issues that might arise.

Rooney, who left her job as scheduler to Sen. Patty Murray, D-Wash., in May to set up the escort and volunteer coordinator office, said one of the biggest takeaways from the experience is that “the Capitol is a lot smaller than it seems.”

“This has totally changed my view of the Capitol Building,” she said. “When I walk around I say, ‘That’s a weird looking little room,’ and that’s why I started this job so early: We did bathroom tours. We have been through every small room that we can possibly use for some purpose for this.”

Incidentally, Rooney has instructed volunteers to ask the packages invited to the Inaugural Luncheon if they need to use the restroom before entering Statuary Hall.