BDEC blank means its still pending. They enter BDEC result in the end of the processing when all background checks(Security check & verification of documents) have finished and they have made a decision +ve or -ve result of the background checks. Our applications are divided into certain sections. I don't think there is a hard and fast rule that this section need to be completed first then only they will move to next section. It all depends on the program manager which way it want to process your application. As you would have noticed from your CAIPS notes our application goes through different departments and the program manager keeps sending the file to different departments and then its returned back to him with the results. Delay from any one department ends up delaying the whole process. One more thing i have noticed is that sometimes the processing of the files are done quiet early than expected but they hold the applications if its still within the normal processing time as they have to spread the no of visas issued throughout the whole year. If you receive a reply saying your file is awaiting background review by an Immigration officer then I think you should assume that the processing of your file has been completed its just now a matter of time when they want to issue the visa according to there quota for the whole year. I am saying all this from my own experience. I am not an immigration expert and I have no intentions to be one. My only intention is to spread as much knowledge i have gained in the last 4 year by reading posts from other experts, information from different websites and combining it with my own experiences. Hope it helps.
Sunny