To be clear, this is what I propose:
LEVEL A: pre-execution level
The malware has been detected before it could be executed.
I would not use the term "browser level". Technically, this term is correct for the AVLab test because all samples are downloaded via a web browser. Anyway, many AVs can detect threats on Level 1 even if the malware was not downloaded via the web browser.
LEVEL 2:
The system level, i.e. a virus has been downloaded, but it hasn’t been allowed to run.
This level probably includes the events that start as Level 1 and end when the sample is moved to another location. The sample is not allowed to run because the analysis has been finished with a delay, and this is not related to the process of moving the sample to another location.
This level could have some value when the samples were downloaded to the network shares and next moved to the local disk. The Level 2 events are very rare in AVLab tests. I propose to join this level with level 1 to get LEVEL A.
LEVEL B: on(post)-execution level
The malware could be executed and has been detected/blocked "on-execution" or "post-execution".
I would not use the term "analysis level", because a similar analysis can be done in many cases on Level A, especially for the files downloaded from the Internet.
As I said, this is only a loose proposition.