Conditional statement in material

Hi,
how can I use conditional statement (if) in material?

condition.png

I didn’t find any info in official documentation about that. I don’t understand how it works. Why A >= B and A < B are on input?. Why A == B and B aren’t highlighted? And what is on output?

Regards,

A and B inputs define the statement arguments. Depends on them, one of three brunches will be used.