A team's exceptions may be lost entirely, or the team may never receive them to begin with. This happens when their team salary is so low that when the exceptions are added to the team salary, the sum is still below the salary cap. If this happens when the exceptions arise on July 1, then the team doesn't get their exceptions at all. If the team salary ever drops below this level during the year, then the unused portions of any remaining exceptions are lost (and do not return if the team salary later increases).
On the Room MLE, Q. 25:
This exception is available only to teams that drop far enough below the cap to use cap room, and therefore lose their Bi-Annual, Non-Taxpayer Mid-Level and Taxpayer Mid-Level exceptions (see question number 26).
Q.1 So, for instance, Boston, who used their RMLE this year on Aron Baynes; that means during the offseason when Boston cleared cap for Hayward, they lost all other exceptions for the year (BAE, MLE,TE, DPE)?
Q.2 When calculating if a team's salary plus exception is lower than the cap, which Mid-Level Exception do they use, Taxpayer or Non?