Dear 863211:
Thanks for your confirmation and help. I know PJiang's sample is enough, the problem is that HR of big insitute won't write the letter in that way.
Especially in NIW case, how do they know the area of your I140. Unless, you show the copy of your I140 and provide a notary certification. They may say it is same with his I 140 area as he told us.
How about in perm case, can people show their LC document to the new employer? just curious. I guess HR just typed his job description, right?