Anybody good at EM? What's the meaning of "Remaining Waits" shown in EM?

What's "Remaining Waits"?

OEM 10g shows us that a sql consumes lots of time, and the breakdown is Application Waits(0.1%)
Cluster Waits(3.7%)
Concurrency Waits(0.2%)
Remaining Waits(52%)
User I/O Waits(21.6%)
CPU(22.3%) But what's "Remaining Waits" which consume the majority of the time? there is no definition on otn or metalink.

The information in another section in EM is: Activity By Time
Elapsed Time (sec) 3,559.97
CPU Time (sec) 795.54
Wait Time (sec) 2,764.43
Here we only have "wait time", and we can see "wait time" take up more than 75% of the total time. I am wondering whether "wait time"(in the section)="User I/O Waits"+"Remaining Waits" (in another section)

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