Letters that make operating instructions
s, a, o, e, g, n, p, c, r, t, i, u are letters that make 'operating instructions'
Words within operating instructions
ER, opera, Opera, pe, ti, ERA, ting, INS, at, ng, on, inst, operating, in, ruction, rating, instruction, CT, instructions, rat, tin, RA, IN, Io, ion, Ra, At, Er, In, Ru, Ti, era, instruct are words within 'operating instructions'