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so, to make this an explicit question:
is the failure to generate a valid design because my syntax falls foul of a restriction that the fcn command should not generate -ve values, or because of some other error on my part?

I am exploring the fcn notation in the design below. I need a set of attributes to add to 10, but the syntax below never finds a valid design.
I know that potentially I will generate a value for alt2.none which is negative, but I am taking the line in the manual as guidence not a rule:
"Care must be ...

I am trying to construct a model where I have a heterogeneous design, with different numbers of alternatives in each model. Page 133 of the manual (version 1.1) suggests its possible, but does not show an explicit example. The syntax below generates the error

Error: The model 'bad' that belongs to ...