I am currently working on a dynamic calculation; my question is with regards to checking the stresses of the system in various time fragments.
I know there are three lines of results for every single node:
1- total stress
2- the highest stress contributor to the above line
3- mode number and direction (sequence number) of the highest contributor

I have done so many dynamic analysis calculations in which I have run into pseudo static cases or missing mass ones ( P and M respectively)
I just wonder if anyone could explain what does that mean when CII gives information like 4 X(B)? or 6 X(C)?

This looks like you're running Independent Support motion response spectrum analysis? The value in parenthesis represents the support group: 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, etc.

No Richard, I don't even know how to group supports...
well, there is a small underground "sleeve" pipe through which, the main piping passes and of course those are connected by some supports.
do you think this led to the weird results?

Support group is appropriate but our input requests defined spectra in your Spectrum Load Case and you will define these spectra based on groups of supports (e.g. group 1 sees spectrum 1, group 2 sees spectrum 2, etc.)

I believe what Rich should have said was: The value in parentheses represents the defined spectrum that causes the maximum response.

Apparently you have many spectra defined in your shock.

With more than one spectrum in the same direction in a spectrum load case be sure to define your Anchor Movement in your Spectrum Load Cases. Oftentimes that oversight causes extremely large (and incorrect) pseudo static loads.

thanks for the response Dave,

I do have 15 time-force spectrums in my analysis and I am down for a time history analysis where, I doubt whether I can define any anchor movements at all.( I thought anchor movement can be defined in Harmonic or Seismic analysis
back to my question; I have set up all of the spectrum directions on X ( it doesn't do anything during the analysis) only for convenience so I can quickly figure which spectrum contributes in the maximum responses. ( the number in the parenthesis represents the sequence number, right?)
generally, I think we often stumble upon flawed results while doing a dynamic analysis on a system which is partially buried; I just don't know how CII would be able to form a mass model for the weightless buried parts?

Of course time history output display differs from the response spectrum results that both Rich & I were assuming. There is no Anchor Movement input for time history (no pseudo static component that could end up as the maximum contributor).
Yes, with 15 time histories all labeled as X will display maximum IDs as X(n) where n=1,2...9,A,B,C,D,E,F. (I don't think we use X(0) for the 10th.)
Buried pipe modeled using the CAESAR II buried pipe modeler does not suit a dynamic analysis. Our focus on buried systems is the effects of soil on pipe strain (and not force-based loads). To use our point restraints to model continuously supported pipe (buried pipe), we cannot have deadweight bending around our supports or weight deflection of our soil springs. With no weight you have no mass; with no mass, no dynamics.
But...with soil surrounding the pipe you probably do not have any dynamic amplification of an applied load - your damping is extremely high and you cannot achieve free vibration.
For dynamic evaluation of the above ground portion, I might suggest modeling your buried pipe just beyond the dive underground and into a level run and add stop with an anchor there. If you are requiring the buried section to remain in the dynamic model instead of an (artificial) anchor, you may want to use a collection of snubbers in your dynamic model to isolate the two sections. And, as you are now, check those results to make sure they can be judged reasonable.