what is "grouped"?what is "spread"?

Hi, I am reading MPC8280 PowerQUICC=99 II Family Reference Manual.
In section 4.3.1.1, it mentioned two words: grouped, spread.
the sentence is like this:
The SIU interrupt configuration register (SICR), shown in Figure 4-10,
defines the highest priority
interrupt and whether interrupts are grouped or spread in the priority
table,

I have some trouble to understand this.

what is grouped? what is spread?

>Hi, I am reading MPC8280 PowerQUICC=99 II Family Reference Manual.
>In section 4.3.1.1, it mentioned two words: grouped, spread.
>the sentence is like this:
>The SIU interrupt configuration register (SICR), shown in Figure 4-10,
>defines the highest priority
>interrupt and whether interrupts are grouped or spread in the priority
>table,
>
>I have some trouble to understand this.
>
>what is grouped? what is spread?
>
>

Grouped interrupts are grouped by priority and are functionally similar. 
I.e. all FCCs are grouped at essentially the same interrupt priority with
rotation.  This is useful in high performance use; e.g. an Ethernet router
might group all FCCs so the interrupts aren't affected by other interleaved
(per interrupt priority) activities in the processor.  Spread are
interrupts  wired to an interrupt priority as dictated by the interrupt
priority table.