Curious: PackageQueues & SpecInstallQueues?

This is just a curiousity: I opened the Enterprise Server JDE.INI to set up multiple batch queues and saw that there were also settings for Package Queues and Spec Install Queues. It looks like these could be specified to be separate queues, or augmented to have multiple or multiple-threaded queues:

[NETWORK QUEUE SETTINGS]
...
PackageQueues=1
PKGQueue1=QB7333
SpecInstallQueues=1
SpcQueue1=QB7333
KillImmediate=1

1) How are these queues used?
2) Would there be any benefit in specifying two separate queues for these (say, QPKG and QSPEC)?
3) Would there be any benefit in defining multiple queues for these, or even setting up multiple-threaded queues?

Thanks in advance.