Code:
#r=rand(max=9, seed=true) # Int, Range 0 to 8, no good (result is modulo 9)
r=rand(max=9,seed=true)+1 # Int, Range 1 to 9
version()
Subtitle(String(r), align=r) # Align=0, is illegal
r=rand(max=8,seed=true)+1 # Int, Range 1 to 9
version()
Subtitle(String(r), align=r) # Align=0 is illegal, 10 too.
In the end to have a randomly moving watermark, rand would have to be evaluated for every frame,
and position be calculated from that, maybe not using align, but this hasn't been asked.