Business visa for a Pakistani National working in Saudi for last 21 years.

I am a Pakistani National 52 years old working & living Saudi for last 21 years. We have a project with a Chines big company and is asked to have a project kick-off meeting in China. Being a Pakistani National the embessy is aking to submitt and an additionl Govt. form. Could u pls. explain as to what this form is. Or an invitation letter attested by Chines chamber of commerce will be sufficient. Best Regards
Abid