白纸黑字 [- - hēi zì]put it down in black and white; (All this) was written down in black and white.; written in black ink on white paper; black characters [letters] on white paper:
•¶白纸黑字, 有案可查。 (The declarations, etc.) are written down and recorded.
•¶白纸黑字, 铁证如山。 These ironclad details are irrefutable proof in black and white.