This should be simply I think, but I'm not certain about the answer. My main breaker consists of four 200 amp breakers gang bared to trip together. Does this mean I have 200 amp main service or more?

Sounds like a GE panel, it should only be 200 amp rating. What does the lable on the panel door state? Can you provide a picture or a model number?

The panel is Siemens, and says it is rated for 200 amps. The four 200 amp breakers suggest that there are four lines feeding two rows at 240 volts for a total of 400 amps. Is this right? What am I missing?

OK ITE makes the similar breaker as GE, this is exactly what I thought you were explaining, it is a 200 amp, not 400. See below the model number it states "200 Amp Max"?

TK, thank you for your answer. I did see the 200 amp max rating, but I wasn't willing to assume it was installed to meet that limit (I have found too many other strange things in this house). So why do I have two sets of 200 amp breakers?

Several manufacturers were making these types of 200 amp breakers for a while. Each half looks like a two pole 100 amp breaker, doesn't it?

If you look inside you will see each half, or two poles, are connected together, as is the other half.

These are actually 2 pole 100 amp breakers, connected in parallel, each half or two poles adding up to 200 amp per leg,which is allowed by code and UL.

I believe they came up with this method to use up the 2 pole 100 amp breakers they had in stock, since the housing industry now uses mostly 200 amp services due to the size of homes and the appliances available.

Siemens does not show this panel any longer, the breaker is probably available only as a replacement. GE still makes this type of Main Breaker panel.