What is Ichi monji kitae in Japanese Katana terminology?

The phrase "一文字鍛え(Ichi monji kitae)" translates to "Straight-line Forging" in English. This is a method used during the process of "Folding Forging" (折り返し鍛錬), where the steel (鋼) is folded and forged in only one direction. This technique is often employed when creating a straight grain pattern (柾目肌) in the base iron (地鉄).