Start Date, Expiry Date - H1B visa

[vyuvarajin]

I am trying to complete the visa application and schedule an appointment for interview.
I found certain particulars under Petitioner like Start Date, Expiration Date, Receipt Number, Name of the Petitioner.
I understood that Name of the Petitioner - should be my employer or petitioner and Receipt Number - should be the number mentioned on my I-129 like WACxxxxxx

I don't understand what is the start date and expiry date?

Start date is it something mentioned on my I-797B like Oct/01/2015 or my date of arrival on USA.
Expiry date is it something mentioned on my I-797B or my passport expiry date. The help message on the site say it is passport expiry date.

[shervin143]

Start date and end date can be petition (I-797) effective date and expiry date.