be (put) down in black and white; black letters on white; commit (sth) to paper (/writing); words being written on the paper in black ❍ 小海挤进人堆，看见一个保丁正把两张封条十字交叉地贴在门上，～上边扣着两个血红的大印。(金敬迈《欧阳海之歌》27) Hai squeezed through the crowd.A policeman was sealing the smith’s door with two crossed strips of paper. In addition to the words written on them in black were two blood-red seals.
白纸黑字bai zhi hei zi
(written)in black and white
白纸黑字
written in black and white 所有这些都是～，有案可查的。All these have been put on record in black and white.
白纸黑字bái zhí hēi zì
比喻有充分的文字证据，不容抵赖或反悔。in black and white, black letters on white paper