Have you ever wondered about what teams need to think about with each transaction? Why a team might put a player on Injured Reserve or Long-Term Injured Reserve, or what the difference is between a Regular Recall and an Emergency Recall?

There is a lot of jargon, and it can be intimidating. But deep down, it really isn't as complicated as it seems. This primer is aimed at helping untangle what the terms mean and some of what a team needs to think about as it makes transactions throughout the season.

There are two basic requirements for a roster:

• The team must have at least 20 players on its active roster, and until the trade deadline cannot have more than 23 players on the active roster
• The team must be under the spending limit

The first thing to think about with each roster move is how it affects the number of players on the active roster and the money available under the spending limit.

A couple of things in that table need more explanation. Let's start with a discussion of waivers.

Some players, as a result of their age and level of experience, are exempt from waivers. They can be loaned to the AHL and recalled to the NHL freely at this early stage in their career. But once the player has been around for long enough, they have to clear waivers before they can be loaned.

When a player goes on waivers, any team in the league can put in a claim. If only one team puts in a claim, then the player is transferred to that team's roster. If multiple teams put in a claim, then the player goes to the team with the highest waiver priority - at the start of the year, that will be the team that had the worst record in the previous season; starting on November 1, it shifts to using the teams' current records. But if nobody puts in a claim, then the player is deemed to have cleared waivers, and then his team has the right to loan him to the AHL.

However, that right to loan him to the AHL does not last forever. The oversimplified version is that it expires when he has played 10 games or spent 30 days on the active roster since the last time he cleared waivers.

The one exception to that oversimplification is if the player is currently on an emergency recall. In that case, the number of days the player has spent on the roster does not matter, and games played while on a regular recall do not matter; the right to send him back down lasts until he has played 10 games while on an emergency recall.

So now we've gotten partway to answering another question that the table above invites: what is the difference between a regular recall and an emergency recall?

The paragraph above gives one answer to that question: there are some instances where a player who cleared waivers earlier in the year could still be loaned to the AHL if he is currently on an emergency recall but not if he is on a regular recall. That is particularly common if he has previously played a few games on a regular recall - for example, a player who played 6 games on a previous regular recall would only be able to play 3 more on a regular recall without needing to clear waivers to be loaned out, but he could play 9 more games on an emergency recall and not need waivers.

Another, unrelated difference between the two types of recall comes in late December. The CBA has a roster freeze around the holidays, during which players cannot be loaned to the minor leagues - with the exception that a player who is on an emergency recall can still be loaned out.

And perhaps the biggest difference between regular and emergency recalls comes after the trade deadline. Each team is permitted only four regular recalls over the 40-day span from the trade deadline to the end of the season, but they can make as many emergency recalls as they need.

Long-term injury reserve (LTIR) gives a team permission to spend above the cap, with the idea being that they might need that room to replace the injured player(s).

The exact amount that they are permitted to spend depends on whether they enter LTIR before or after opening night and on what their payroll and cap space looks like on the day they enter LTIR. But in general, the most important consideration is that they want their payroll to be as high as possible on the day they enter LTIR. Their spending limit for the entire time they are in LTIR will be related to their payroll on that date, so it is common to see a team add players to the roster to maximize their payroll on the day they go into LTIR - that locks in the favorable spending limit, which remains the limit even if they loan those players back to the AHL soon after.

LTIR can help a team make additions, but it does carry some disadvantages compared to being under the cap. Imagine a team starts the year with $1M of cap space and somehow gets through the whole year without a single transaction; they will end the year $1M under the cap. If they had players earn performance bonuses that year, the first $1M earned will be applied to the current year's cap - there will only be a performance bonus rollover to the next year if players earned more than that.

In contrast, imagine a team spent the whole year in LTIR, but $1M under their spending limit. Performance bonuses can only be applied to the current year if the team is under the cap; if they used LTIR to spend over the cap, it doesn't matter that they had LTIR room to spend even more - they will still have to roll all of their bonuses over into the next season, and will have less room to work with as a result.

Another advantage to being under the cap is the way cap space can accrue. Suppose that team with $1M of cap space gets 3/4 of the way through the season and decides they want to add a player. They are on pace to finish the year $1M under the cap, so they have enough room to take on a player with a $4M cap hit for the remaining 1/4 of the season. Their $1M of spending power has quadrupled!

In contrast, LTIR space does not normally accrue in the same way. The team that has been $1M under their spending limit all season still only has $1M to spend at the trade deadline.

One other way of adding players beyond the normal spending limit has been used increasingly often in recent seasons, as teams have spent closer to the limit than ever before and been less inclined to save some cap space for an emergency. The NHL's hard cap system can sometimes put a high-payroll team in a situation where they simply do not have spending room to add a player. If that happens and the team loses a player to illness or injury, the CBA has a provision to allow them to address it.

First, the team has to play shorthanded for a game, to dissuade teams from relying on this provision and to establish that they have a true roster emergency and are not simply looking to get around the salary cap. Then, before the next game, the team can recall a player to replace the injured player; that player will receive his normal NHL salary but will not show up on the team's cap accounting at all. This provision is limited to players whose pay is near the minimum - their contract's average annual value, including all bonuses, cannot be any higher than $100k above the minimum salary for that season.

Or those are the rules in normal times, anyway. But for the 2020-21 season and the latter half of the 2021-22 season, rampant COVID outbreaks led to temporary rules changes aimed at making things a little easier on a team hit by the virus. Under these temporary rules, the player called up can have an average annual value of up to $1M, rather than the $850k that would be typical in a season where the minimum salary is $750k. Also, under these temporary rules, a team can sometimes invoke the roster emergency exception without playing short first; that happens when either (a) the emergency situation would leave them with fewer than two goaltenders, or (b) the emergency situation arose because of a COVID outbreak.

As you see transactions announced throughout the season, hopefully this primer will help you understand a little bit of the nuance behind each action.

When you see a player get moved to IR, you will know from our table that the only impact is that it removes them from the active roster, and you can think about why removing him from the active roster might have been beneficial. When the team has injuries and announces a recall, you will know the pros and cons that the team weighed when deciding whether to make it an emergency recall.

No primer can cover every possible situation, of course. So when you see something that isn't covered here and are wondering how to interpret it, send a message to @WaltRuff on Twitter.