Jiujitsu rules for Competition and differences around the world

Hi Guys,

We were having a cool conversation in the JJ dojo that I workout in. Basically the conversation was about the differences about JJ competitions rules all over the world. The sensei is Russian/Dutch so he is used to European rules. I started training JJ in Japan so I am used to Japanese rules. There are other guys there that just do wrestling. One of the things that came up was about open hand chokes. I don't think you can use knife hand chokes in Japanese tournements. The sensei said that you can use them in European tournements. How is it in the US? Do you see them?
In Japan, for example, you can't put your fingers in the sleeve of you opponent but you can grab the sleeve and roll it up and use it that way. These days you also see more locks than chokes in Japan these days. Are chokes popular?
What differences do you guys see? What are the rules in the US competitions?

Thanks,
JD