Below are a few questions, nits, suggestions.

The description in 4.6.2 is confusing. If the first condition causes Q to be removed, then if R is successful, Q no longer exists.  Then how can R be further processed?  The logic here should be better organized. 

4.6.3 “the timer should examine and possibly refresh its state” -> “the timer should be examined, and its state are possibly refreshed”

When mentioning a particular state or status, it’s better to put it in quotation marks or capitalize it to avoid confusion. For example, early, sent, unsent, success, …

Pg.18 “For example, What if …” -> “For example, what if…”

4.6.11 “a encrypted” -> “an encrypted”