Web Reporter uses block_res to populate the action (block, allow, warn, etc) and the reason (due to malware, due to category, etc.). Because of this, the block res needs to be in the specific set of default values used by Web Gateway. However, this is the mapping range that you can use for your own custom block codes. You should not that there is no range for "allow" since allow is either 0 or "no value".
MWG (6 & 7) Action | WR Action | WR Action Range
Coaching | Warn | 200 - 299
Coaching Redirect | Bypass | 300 - 399
Override Redirect | Override | 400 - 499
What range used for block reasons ?
Are you asking if there is a range for "block"?
I did a quick test using these values and they were all block (500, 550, 670, 2000, 3430). So I would assume anything not in our ranges (including the large set of values under 100) would be considered a block. Basically any high number above 499 should be a block action.