[math-fun] Q about terminology for D0L (Lindenmayer) systems

For Lindenmayer system, say Axiom: L Rules: + --> + - --> - L --> L+R R --> L-R the "development" (or whatever it should be called) goes as 0: L 1: L+R 2: L+R+L-R 3: L+R+L-R+L+R-L-R 4: L+R+L-R+L+R-L-R+L+R+L-R-L+R-L-R ... What should I call the word in the n-th line? I used (n-th) "iteration" or "generation" but neither sounds very good. Any better ideas? Best regards, jj