positive ignitions are a good thing, well safe anyway, its an indication your tune is very conservative if they are as high as +10.
Negative ignitions are a result of the engine knocking or the fuel detonating early because of excess heat or too much ignition timing, aka too aggressive of a tune for the fuel you are using. There isn't really an agreed upon value for safe negative ignition corrections, staying at 0 or slightly positive is best but going slightly negative such as -1.5 is perfectly fine. Your octane adjust ratio will also adjust the tune continuously to keep it safer.