Sequencing is the act of putting things in an order — first, then next, then after that. A teacher may talk about sequencing a story: what happened first, what happened later. In a factory, a kitchen, or a computer program, sequencing is lining up the steps so each one comes at the right time. Scientists also use it for reading the order of the tiny letters in DNA; that is the same idea, just used on genes. The word names the arranging, not the line itself. The line is a sequence; making the order, or setting it, is sequencing. It is a calm school-and-work word, not slang, and it does not by itself mean “making a film” (that is a different sense of sequel/sequence in cinema talk).