1) When i was doing analysis for a trajectory for a 20ns simulation with 2000 frames with:
"coor hbond verbose sele monitor end sele .not. monitor end firstu 20 nunits 1 begin 10000 skip 10000"

the following was observed in the output:
Analysis of hydrogen bonds using cutoff distance= 2.40 and angle= 999.00
Total time= 977.8ps. Resolution= 0.49ps
Occupancy cutoff= 0.00 Lifetime cutoff= 0.0ps

>> why only 977.8 ps?

2) the spec "skip" and "nskip" for the traj-spec is same?