Supporting documents for US visa application?

hi, the US embassy in manila may request us some evidence of ties to the philippines. these are may or may not be requested but still we have to prepare them, INCOME TAX RETURN (BIR) FORM, WEDDING PICTURES, LAND TITLES to name a few. but mentioned are PHOTOCOPIES WILL NOT BE ACCEPTED, UNLESS SPECIFIED, ANY DOCUMENTS RECEIVED WILL NOT BE RETURNED AND WILL BE DESTROYED. what kind of documents that will not be returned and be destroyed? are the important supporting documents such as wedding pictures, titles etc be borrowed only by the consul during the interview?