what should i write in the Local ID section in the application form ?

i am Egyptian citizen welling to travel to China to visit some factories to select some machines to buy m i already got an invitation letter .
Please advice what should i write in the local ID field in the visa application form ? do you mean my Egyptian ID number ?
Also do i need to write an authorization letter to someone else to submit my visa applications and documents to the embassy instead of me ? or he can submit it without authorization letter ?