Astra G Z14XE ignition angle, cylinder knock

[vsz]

Hello,
Could you please provide an explanation on the Spark ignition angle and the cylinder knock values?
What is a good value, what refers to a problem?
When driving at a constant speed I have 3 cylinders with near 0 value, but 1 cylinder with 20-25 value. What would cause this?
I don't have a screenshot, but if necessary I can post one later today.
Thank you

[vsz]

I could not attach a screenshot of the section I would need help with, the forum won't allow it.
Anyhow, below the name of what I would need help with.
Ignition dwell angle
Ignition spark angle
Retard knock for the 4 cylinders.
What do these mean, what is considered normal and what suggests there is an issue?
Any tips welcome.
Thanks