Not sure of any good online material, but basically, a type 1 hit is generally joint pain, generally on the veinous side.
A type 2 hit is neural... brain or spinal, and caused by bubbles migrating to the arterial side.
The two may be confused though, as injury to the brain or a nerve can mimic virtually any kind of tingling/numbness, or pain.
It may seem as if a type 1 hit could possibly be ignored, and often, if it is only minor joint pain, it may go away by itself, but there will still be damage that may or may not fully heal.
EITHER type can be deadly, as can AGE. I would not recommend ignoring even a type 1 hit, in part because WE are not qualified to properly diagnose the type or level of damage. That "type 1 hit" may be a bubble lodged in a part of the brain that tells you that your elbow hurts, and hours later while lifting your tanks out of the boat, the vessel could expand, allow the bubble to move on, and cause a stroke.
In both cases though, the first symptom is identical....
Denial.