Here’s the thing about the Phillies’ training-camp roster -- and, really, everything else that pertains to this season-within-a-pandemic: It isn’t set in stone.

More like paste, actually.

Players who weren’t on the roster Sunday could materialize as soon as Tuesday. There will be temporary subtractions -- “a handful, at minimum,” general manager Matt Klentak said on a 40-minute Zoom call Monday -- when players test positive for COVID-19 or learn that they have been exposed to someone who is. The door isn’t closed on anybody, not even outcast outfielder Odubel Herrera.

The most common answers from team officials over these next few weeks will be "I don't know," and they aren't being evasive. In a season unlike any other, with 101 pages of protocols from Major League Baseball and a deadly virus that keeps moving the ball, there's a lot to digest and little time to do it.

For now, Klentak can say this much: He doesn't expect any Phillies players to opt out of the season, a la Arizona Diamondbacks pitcher Mike Leake, Washington Nationals pitcher Joe Ross and teammate Ryan Zimmerman, the 35-year-old first baseman who has been a part of every season since the franchise moved from Montreal in 2005.

Even right-hander Zack Wheeler, whose wife is 8½ months pregnant, likely won’t miss much more than the “typical paternity leave list time” of a few days, according to Klentak, who added that he isn’t aware of coaches opting out, either.

Beyond that, though, Klentak isn’t sure about much, which explains why the Phillies left seven vacant spots on the initial 60-player camp roster that they turned into MLB on Sunday night.

“There’s enough uncertainty with COVID, with the rules that are constantly being adjusted, with players traveling in,” Klentak said, “we wanted to make sure we preserve the ability to adjust. We thought it was best to leave some room. We can always add.”

Veteran reliever Anthony Swarzak will be one of the first additions, after the Phillies finalize a slight restructuring of his minor-league contract. Klentak said the Phillies expect to add a few more catchers, too. Most teams included five or six on their training camp rosters; the Phillies have only three (J.T. Realmuto and backups Andrew Knapp and Deivi Grullon).

Herrera, removed from the 40-man roster in January after serving an 85-game suspension without pay last season for violating MLB’s domestic violence policy, also will “continue to gain consideration,” according to Klentak, which doesn’t set him apart from several other minor-leaguers who have not yet made the cut.

It’s likely, though, that the Phillies hold off on additions until they get the results of players’ intake screenings, which includes COVID-19 testing. Seven players, mostly major-leaguers, were infected this month in an outbreak at the Phillies’ facility in Clearwater, and it’s “probably too soon to tell,” Klentak said, if they will be on schedule to begin camp.

Klentak wouldn’t reveal the identities of the players but confirmed that some experienced “flu-like symptoms and fevers that lasted anywhere between a few hours and 24 hours.” But MLB’s protocols stipulate that anyone who tests positive must receive two negative tests 24 hours apart before they can rejoin the team.

“We already have some distance to when a lot of those guys tested positive,” Klentak said. “But the league and the union have negotiated some pretty clear guidelines for returning to the ballpark after a positive test. As soon as these guys are healthy and physically able to report, then we will get them on the field.”

There’s a separate injured list for players who test positive for COVID-19 or have been exposed to it. Those players can be replaced in the 60-man pool, and when they return, their replacements need not be exposed to waivers. Just another of MLB’s virus-related wrinkles.

The Phillies have been working out the logistics of holding a 60-player camp at Citizens Bank Park and their youth academy at nearby FDR Park. They have had to arrange the clubhouse, weight room, training rooms, and other facilities to be compliant with social-distancing protocols.

And when the team holds its first formal workout Friday, it won't look anything like a typical spring-training routine for reasons that go beyond merely the staggered workout times and small groups that will be split up into morning and afternoon sessions.

"It's not going to be surprising to see a guy doing weight-room workouts on the concourse," Klentak said. "That's something we're contemplating just to give guys a little more room to maneuver."

It all underscores the immensity of this undertaking. Unlike other leagues, including the NBA, MLB isn’t taking a “bubble” approach to the season but rather attempting to play in 30 cities at a time when new cases are rising in baseball hotbeds such as Florida, Texas, Arizona, and California.

“It’s going to be a challenge,” Klentak said. “We saw an outbreak take place in Clearwater, where we had half a dozen players, and it can happen fast. Now, we’re going to have 53, and 30 teams are going to have that with more staff. And you’re going to layer in travel.

“It’s going to take a lot of discipline from a lot of people. It’s going to put a lot of strain on the testing process. The importance of testing every couple of days is going to be critical to the operation, as is the discipline of the people to stay safe.

“Everybody wants the same thing. We want baseball to come back. But just because we announced we’re coming back doesn’t mean we can take our foot off the gas. We need to make sure that we double down on our efforts to make sure that when we are back we stay back.”