@ Mitali, as per the format of the letter they have send that, what I have understand that, when an application is reached there they allocate it an immigrant file no, and if they find application incomplete or find any information not provided, they ask for the information from the applicant. This information include fees, incorrect form, unsigned form, incorrect description of duties, invalid Visa office. there is a checklist in the document. I will try to post the scanned copy of letter 2day. They didn't send the whole application back, just a letter and appendix stating what information is required.
I think returned is wrong word i have used, it must be they have put application on hold, and need more information for processing. Application of those are returned who didn't score the required points, otherwise rules are flexible.