Zttest, ztmonitor, ztclock, ztspeed

Can someone point me in the right direction for detailed information on these utilities?

My general questions are about how they should be used ofr troubleshooting, tuning. Do they have any relevancy for SIP trunked setups, no dig/analog cards?

I have a Dell 1550 I am struggling with, no overlapping IRQs, lousy zttest output though. Low of 97, average of barely 99 and never a 100. Should I care?

What does ztspeed tell me? What are reference points for ztclock? Should I care if I am only using SIP trunking?

I have exhausted ideas for search and I woudl like to RTFM but can’t find one.