ModelingToolkit -- limits to parameter blocks, etc.?

Specific Domains Modelling & Simulations
1

Assume I create a ModelingToolkit “instantiator”, say:

@mtkmodel Tank begin
@structural_parameters
    case = :std
@parameters begin
    ...
end
@variables begin
    ...
end
@equations begin
    ...
end
end

Questions:

  1. Is it permissible to have more than one “block” of each type, e.g., can I split parameters into two @parameters blocks, e.g.,
@parameters begin 
    a = 2
end
@parameters begin 
    b = 2
end

Would this be the same as?

@parameters 
    a = 1
    b = 2
end
  1. If yes, can I do the same for other “blocks”, e.g., @variables, etc.?
  2. Can I mix the order?, e.g.,
@parameters begin
    a = 1
end
@variables begin
    x(t)=5
end
@parameters begin
    b = 2
end
@variables begin
    y(t) = 3
end
  1. Can I have several tests of parameters/structural parameters in the equation block? E.g.
@equations begin
    if case == :std
        x ~ 2y
    else
        x ~ -2y
    end
    y ~z
    if case == :std
        w ~z
    else
        w ~ -z
    end
end

or do I need to collect cases in a single block?

[I’m getting very strange results when instantiating the model… goes from working to giving warning/error message if I put an equation into an if-test, even if the if test is true…]