Format and bad sector questions

[DiscBuster]

I'm trying to understand the formatting and bad sector mapping process in Blu-Ray discs.

I have a few questions. All questions are for Blu-Ray discs only:

1. As I understand from the ImgBurn guides, when "Prefer Format With Full Certification" is enabled, the drive tests all sectors and maps out any bad ones.
    
    1a. How does the drive test the sectors? Does it write something, read it and compare? If this is the case, does it write back the original content of the tested sector?
    
    1b. What happens if no spare area is allocated and the drive finds a bad sector? Is the spare area automatically allocated if certification is selected, regardless of the selection for the spare area?

    1c. Are the bad sectors mapped only during the certification process, or can it happen during the data writing process as well? If so, should the option "BD-R verify Not Required" or "BD-RE FastWrite" be unchecked for it to happen?


2. Once bad sectors are mapped, how can we list the bad sector table, or at least find out if there are any bad sectors on the disc?

3. I found out even a BD-R can be "erased" fully and the format options have an effect on the BD-R erase, though they are supposed to be for RE media. With BD-R media, I assume a certification cannot happen and bad sector finding should take place during data writing only. Am I correct?

4. I've experimented with almost all combinations of format options and verify and FastWrite options, but no matter what options are set and how the disc is formatted, whenever data is written to the disc ImgBurn always reports, "Hardware Defect Management Active: No". From this I assume the format options and bad sector allocation during certification are different to "Hardware Defect Management". What exactly is "Hardware Defect Management" and how can it be enabled?

5. Under disc information, what is "scanned" status? It always appears as "no", even when "certified" is "yes". What is the difference bewtween "certified" and "scanned"?

6. As I understand, UDF 1.5 or higher supports bad sector mapping at the filesystem level. Does ImgBurn support it? If so, how do we enable it?