The NBA returns to regular-season action on Dec. 22 following an abbreviated offseason -- one that saw the draft and the start of free agency compressed into the same week -- with some uncertainty.

With the coronavirus pandemic ongoing, the league is facing decisions about how to undertake a campaign outside the relative security of a bubble. While the NBA circulated a 134-page guide to health and safety protocols last week, there are still outstanding concerns needing to be addressed.

Here's what we know and don't know about how the 2020-21 season will work.

What happens if and when a player tests positive?

Any time a player tests positive for COVID-19, he will have to go through a series of steps before being able to play again.

If the player is asymptomatic, he must sit out for 10 days from when first testing positive, then pass a cardiac screen and, finally, work out alone at the team facility for two more days before being allowed to return to full team activities -- assuming there are no issues.

If the player is symptomatic, he must sit out for 10 days from when symptoms subside, then follow the same path as asymptomatic players.

If a player gets a serious case of COVID-19 -- up to and including having to go to the hospital -- he would have to work out alone for three days, rather than two, before being cleared to return to team activities, assuming everything checks out.

Basically, fans can expect that if a player tests positive, he will be unable to play for at least two weeks -- and if he shows any symptoms, that time frame could very easily grow longer. -- Tim Bontemps

What happens if an individual or a team breaks COVID-19 protocol?

As of now, it remains unclear how the NBA will handle any potential fines for breaking COVID-19 protocol. The league is still finalizing how it will handle potential violations, but expect the NBA to follow the NFL's lead in that fines will likely vary depending on the severity of each violation.

The NFL has fined a number of teams for not properly wearing masks, but it also fined Washington Football Team quarterback Dwayne Haskins Jr. just under $5,000 for making a reservation for a family friend at the team hotel. -- Nick Friedell

Will games be suspended for positive tests?

Much like the NFL, any potential game suspensions or postponements will be reviewed on a case-by-case basis. NFL teams have tried to play through the schedule when only a handful of players test positive in an organization, but schedules have had to be altered in outbreak situations.

The NBA remains confident in its protocols, but it remains to be seen how it will handle the situation if several players on one team test positive at the same time. -- Friedell

How is the season schedule different?

The schedule will be different in a few ways.

First, there will be only 72 games -- down from the typical 82. While teams are still scheduled to play at home and away against every team in the opposite conference, they will play only three times against every team in their own conference. Typically, teams play four games against 10 opponents in their own conference and three against the other four.

Second, in an effort to reduce travel, teams are expected to play what can be described as "baseball-style" series against opponents, with two consecutive games in the same city against the same team. Fans will get a small taste of that during the preseason, when there will be several repeat matchups between teams.

Finally, rather than releasing the entire schedule all at once, the NBA is going to release it in halves. The First Half will be released later this week, and the Second Half will be released after about 30 games have been played. This gives the NBA flexibility to adjust to possible postponements due to COVID-19 issues. -- Bontemps

Will there be fans at games?

That decision will be made on a team-to-team basis in consultation with local and state health officials. No fans will be permitted in several NBA cities at the start of the season. Other cities will allow a limited number of fans -- with all fans over the age of 2 required to wear face masks.

The Memphis Grizzlies announced that the capacity in FedExForum "is expected to be roughly 20%," based on socially distanced seating configurations, to start the season. The Utah Jazz announced a plan to have a reduced seating capacity of 1,500 in the lower bowl only and limited seating on the suite level. The Atlanta Hawks plan to have friends and family in the stands in the first weeks of the season and 10% capacity for their Martin Luther King Jr. Day game, the Atlanta Journal-Constitution reported. Several other teams are in the process of determining what their seating capacity will be to begin the season.

The Golden State Warriors' "Operation Dub Nation" plan to fill the Chase Center to 50% capacity -- a proposal that included rapid COVID-19 testing for every person who entered the arena -- was rejected by the San Francisco Department of Public Health.

"In the present circumstances, bringing thousands of individuals (and households) together -- many of whom would travel and return from other counties -- creates too much risk of widespread transmission in transit and while visiting San Francisco," the department of public health said in a letter to the Warriors, according to the San Francisco Chronicle.

Other franchises, including the Oklahoma City Thunder, Denver Nuggets and Charlotte Hornets, have announced they will open the season without fans at home games.

"We are optimistic that conditions will improve in the coming months and hope to be able to have fans in attendance later in the season," the Hornets' statement read. -- Tim MacMahon

What are players allowed and not allowed to do on the road? And how have traveling parties changed?

In the past, there was no limit on how many people teams wanted to have along on trips; it was strictly a matter of how many they were willing to pay for to take on the road. Now, though, there is a hard limit of 45 people who can be part of the travel party. For some teams, that won't matter. For others, it will cause major headaches.

As for what players will be allowed to do on the road, that is still unclear. In the health and safety protocols sent to teams ahead of training camp, all it said on this topic was: "As when in their team's market, members of the Traveling Party shall remain obligated to minimize risks to manage their health and enhance that of all individuals involved in the 2020-21 season. Further information regarding permissible traveling party movements is forthcoming." -- Bontemps

How will the league handle cities potentially instituting bans on games and practices?

The Toronto Raptors have already had to temporarily relocate due to pandemic travel restrictions the Canadian government has put in place that made it infeasible to have an NBA team based north of the border for now.

The Raptors chose Tampa, Florida, as their home for an indefinite period after considering several other sites.

Other situations requiring a franchise to temporarily relocate would be handled on a case-by-case basis. Teams and the league office are in frequent contact with local and state officials, discussing protocols and seeking government guidance, so the hope is that a team won't be caught off guard by such a situation arising.

The league has an idea of which cities have the infrastructure in place to host an NBA team, but there isn't an official list of alternate cities at this point. Potential relocation cities would be evaluated solely on health and safety issues, as factors such as fan support would not be relevant. -- MacMahon

How are player salaries affected?

While the season is 10 games shorter this season, player salaries will remain the same. What is going to change is the amount of their pay that is withheld in an escrow fund. Because the players and the league essentially employ a 50-50 split of basketball-related income (BRI), the players typically get 10% of their pay withheld until the end of the season to make sure the books are properly balanced. Then, depending on the way the revenues play out as compared to projections, both sides will square things up at the end of the season.

This season, however, revenue is all but certain to be lower than the 10% withholding could make up. As part of the negotiations to bring the league back for the 2020-21 season, the two sides agreed to have an escrow of no more than 20% this season and to spread the losses out over the next three years to make sure that no single class of players was impacted too heavily. -- Bontemps

What's happening with the All-Star break?

The NBA will not hold an All-Star Game this season, but there will be a break in the action from March 5 to 10, separating the two halves of the season. Players will get six days off in the middle of what figures to be a hectic schedule. Whether All-Star teams will still be named is yet to be determined.

Indianapolis, which was scheduled to hold the 2021 All-Star Weekend festivities, will now host in 2024. -- Andrew Lopez

When is the trade deadline?

The 2021 trade deadline has yet to be finalized. The deadline is typically in early February, a week or two before the All-Star break, but this season's deadline will occur after March 3. That is the date when free agents who signed with their own teams for greater than a 20% increase from the previous season can be traded. -- Royce Young

How will the play-in tournament work?

After the success of the play-in tournament in the bubble, the NBA officially implemented and expanded the play-in tournament for the 2020-21 season. The NBA board of governors unanimously approved the play-in tournament on a one-year basis for this season.

Four teams -- the Nos. 7-10 seeds in each conference -- will make the play-in tournament. The teams with the seventh- and eighth-highest winning percentages will have two chances to make the playoffs, while the teams with the ninth- and 10th-highest winning percentages will have one chance.

The "Seven-Eight Game" will be between the teams ranked seventh and eighth, while the "Nine-Ten Game" will feature the teams ranked ninth and 10th. The winner of the Seven-Eight Game will advance to the playoffs as the No. 7 seed. The loser will host the winner of the Nine-Ten Game, and then the winner of that contest will get the eighth seed in the playoffs.

The play-in tournament is scheduled for May 18-21. -- Lopez

Will there be a playoff bubble?

It is too early to say. The NBA isn't even releasing the full schedule yet, so there isn't any formal plan for how the playoffs might look. There is built-in flexibility for how the NBA is planning to approach the season, and while a playoff bubble could be a possibility, if needed, the hope for the league would be to have the postseason be as "normal" as possible, including fans in the arenas. But exterior factors will determine much of that, and it's impossible to predict what the situation might be in June. -- Young

What would it take for the NBA to suspend the season?

It remains unclear. In the health and safety protocol, this is what the league said with regard to the potential for suspending the season: "The occurrence of independent cases or a small or otherwise expected number of COVID-19 cases will not require a decision to suspend or cancel the 2020-21 season."

The document goes on to say it is designed to "promote prevention and mitigation strategies to reduce exposure to, and transmission of, the coronavirus," but that it is likely some players and staff will contract the virus.

The fact that this is left so open-ended is an indication that the NBA is well aware of the difficult road ahead. Already we have seen two Warriors players and one Washington Wizards player test positive, according to those teams.

After seeing the complications the NFL and MLB have had in playing their seasons outside of a bubble format, we know that the NBA has the potential for similar issues. -- Bontemps

ESPN's Bobby Marks contributed reporting.