i have attached a sample programm which fails to set a subsample using the smpl command. The error seems to come from the name of the variable used.
gretlci (Version 1.8.0) gives the following error when executing.
? scalar estim_length=1
Generated scalar estim_length = 1
? smpl +estim_length
realgen: exiting on lex() error 15
error in new starting obs