better to bring the entire approval notice with you!
My company lawyer specifically told HR and me that the ENTIRE approval notice is needed for visa application, despite the deion on the I-797.
You should ask for the entire piece of paper from your employer (not only the lower section) to bring with you to US Embassy in China for H-1B visa application.
Hint: You want to make copies of both sides of it to keep a record, and VO in Embassy wants to keep a copy too.
Good luck!