We need $M$ to be (symplectic) Calabi–Yau and $L,L^{\prime}$ to be graded to define the degree $\mu_{L,L^{\prime}}(p)\in{\mathbin{\mathbb{Z}}}$, which determines the grading of $CF^{*}\bigl((L,E),(L^{\prime},E^{\prime})\bigr)$ and $HF^{*}\bigl((L,E,b),(L^{\prime},E^{\prime},b^{\prime})\bigr)$. If we took $M$ symplectic and $L,L^{\prime}$ oriented, then $CF^{*}\bigl((L,E),(L^{\prime},E^{\prime})\bigr),HF^{*}\bigl((L,E,b),(L^{\prime},E^{\prime},b^{\prime})\bigr)$ would only be graded over ${\mathbin{\mathbb{Z}}}_{2}$ rather than ${\mathbin{\mathbb{Z}}}$.