How does CO verify my employment?

Any advice is appreciated:) I wonder when CO contact the employer to verify visa applicant's employment, what sort of information or documents will they ask for other than the job reference letter? I need to get my boss prepared for that. He is very busy and I'm thinking to gather all the documents issued by the company in one place for his reference since he is not HR and not overlooking the payroll. I have so far provided DIBP with payslips, employment contract, job reference letter, group certificate, tax return, super statement and bank statements....
It depends on the CO. email/call or scan the document and send to the provided company/contact email ID to verify any or all of the information stated in the letter.
if you see my case you can get this ans, I was verified for employment verification by Aus High commission New Delhi, In worst case if your employer fails to provide any info, they will call you.
Hello Cain. I am also facing with this issue. My boss is the VP of 4 companies located in China, Japan, Vietnam and Indonesia. He is flying among these countries monthly. I am afraid he is too busy to answer a call from the CO and would like to have an appointment before any contact. How was your case solved? Thank you!
Verification will be done by HR dept. They won't call your boss straight away.
@ Saadi : Thank you for your reply, but the HR dept is under my management and they can't speak English...
W
Will they call only to the latest company?