The browser parser uses three question marks to flag unparsed (hex converted) log entries in the binary file from the Zero app that are of unknown types. Since the serial cable event log dump is fully decoded text, it is possible to compare entries with matching timestamps from the parsed binary log text and the serial cable log dump. This is how I found the previously unknown entry types. I search the parsed text for unknown entries and then find matching entries from the serial log. There is a time zone correction needed, three hours in my case between local parsed timestamps and factory time zone log entries. The surrounding entries before and after the unknown one confirm the match.
From cable
06591 06/16/2017 17:34:46 Charging PackTemp: h 31C, l 30C, AmbTemp: 40C, PackSOC: 14%, Vpack: 98.951V, BattAmps: -2, Mods: 11, MbbChgEn: Yes, BmsChgEn: No
06592 06/16/2017 17:36:04 BMS Isolation Fault BMS: 0
06593 06/16/2017 17:37:33 BMS Isolation Fault BMS: 1
06594 06/16/2017 17:44:42 Low Chassis Isolation 22 KOhms to cell 1
From Browser parse
08290 06/16/2017 20:34:46 Charging PackTemp: h 31C, l 30C, AmbTemp: 40C, PackSOC: 14%, Vpack: 98.951V, BattAmps: -2, Mods: 11, MbbChgEn: Yes, BmsChgEn: No
08291 06/16/2017 20:36:04 0x31 0x00 0xb2 0x08 0x31 ???
08292 06/16/2017 20:37:33 0x31 0x01 0xb2 0x0c 0x3a ???
08293 06/16/2017 20:44:42 Low Chassis Isolation 22 KOhms to cell 1