= Solution
Index chocolate by $a\in\{A,B,C,D\}$, day by $d$ in the three observed categories, and replicate by $r\in\{1,2\}$. The additive <two-factor normal linear model> is
$$
Y_{adr}=\mu+\alpha_a+\gamma_d+\varepsilon_{adr},\qquad
\varepsilon_{adr}\overset{\mathrm{iid}}\sim N(0,\sigma^2).
$$
Here $Y_{adr}$ is the board count, $\mu$ is the mean for the reference chocolate and reference day, and $\alpha_a,\gamma_d$ are chocolate and day <fixed effects>. With <corner-point constraints>, set $\alpha_A=0$ and $\gamma_{d_0}=0$, where $d_0$ is the first level in the day factor. The printed coefficient-free output does not determine that factor ordering; the model is unchanged by a different reference category. There is \b[no chocolate–day <interaction term> in this fit]. The six free mean <statistical parameters> consist of one baseline, three chocolate contrasts and two day contrasts; the common error <variance> supplies a further <statistical parameter>.
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