Business letter format in China

[zerolife]

Is the format of a business-to-business letter in China different than what's used in the US/EU?

I came across the following article which mentions including a reference number and fax number below the company letterhead. Is that a must?

http://owl.english.purdue.edu/owl/resource/676/01/

Thanks for any help in advance

[Scoobyqueen]

I thought the first sentence of the opening paragraph needs to be indented espcially for a formal business letter.