Another article from Knowledge Base. According to it Priority[] is setting some default value which will be assigned when interaction will enter the queue.
[i][b]Question Detail[/b]
What are Internal Queue's in URS?
[b]Answer[/b]
Explanation on Internal Queue.
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When you select some target set (agent group, skill expression, etc.) for a call and specify a VQ for it, URS creates an internal queue, which is identified by target set name + VQ name, and puts the call into this queue according to its current default priority (the default priority is set by Priority[] function). If an internal queue with such identifier already exists, URS is using existing one.
For example, you put a Call1 to wait for AG1 target in VQ1, then you put this call to wait for AG2 target also in VQ1. Internally URS creates two queues: AG1+VQ1 and AG2+VQ1. In every of these queues the call took its position according to its default priority. When you call a SetVQPriority function for this call in VQ1, URS will recalculate the call position in all internal queues having the "VQ1" in the identifier (both AG1+VQ1 and AG2+VQ1 in our case) and save the specified priority (N) for this call in these internal queues (please note that the default call priority is not changed by SetVQPriority call). Continuing our example, a Call2 has arrived and is put to wait for AG3 target in VQ3 and AG4 target in VQ4, URS creates two more internal queues (AG3+VQ3 and AG4+VQ4) and puts the call into these queues. Some agent become ready and this agent belongs to, for example, AG1 and AG4. URS takes the call from the head of every internal queue having the AG1 or AG4 (AG1+VQ1 and AG4+VQ4 in our case) and routes the call having the highest N number.
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