What does "1.2 psrms integrated jitter" mean?
1.2 ps rms jitter can be considered the standard deviation of random noise for some sample size.
This can be converted to +/- peak jitter , if you choose a sample size.
This can also be translated into the frequency domain as some noise below the peak carrier power off center frequency in a 1 Hz band or dBc/√Hz.
This will show you how.

So if your clock has a jitter of 1.2ps rms then over a sample of 10^9 transitions this is equivalent to a peak jitter of 7x or 8.44 ps.  Then adding this to the data jitter, you can correlate this to a bit error rate curve  (BER) in [ps per decade] in some other question for yourself, when you understand all the variables for bit rate, clock rate BW , SNR, Peak jitter, decoder gain and noise spectrum.
salam.