= Solution
For the body-centered tetragonal direct lattice, conventional reciprocal labels $(h,k,l)$ are integer triples satisfying $h+k+l$ even. This follows because the extra translation $(1/2,1/2,1/2)$ must have phase one for a <reciprocal lattice vector>. In the $k=0$ section the condition is $h+l$ even. The reciprocal steps are
$$
\boxed{a^*=\frac{2\pi}{0.353}=17.799\ \mathrm{nm^{-1}},\qquad
c^*=\frac{2\pi}{1.05}=5.984\ \mathrm{nm^{-1}}.}
$$
Within the strict index window $-2<h,l<2$, the reciprocal points are $(h,l)=(0,0)$ and $(\pm1,\pm1)$. The neighboring $(\pm2,0)$ and $(0,\pm2)$ points lie on the excluded boundary but are useful for constructing the zone bisectors.
At the requested drawing scale, one conventional step in $h$ is $a^*/5=3.560$ cm and one step in $l$ is $c^*/5=1.197$ cm. Thus the four off-origin included points have drawing coordinates $(\pm3.560,\pm1.197)$ cm. Keeping these unequal physical scales avoids drawing a fictitious square reciprocal section.
\Image[/past-exam-of-the-condensed-matter-physics-major-option-course-of-the-university-of-oxford/2015-body-centered-tetragonal-reciprocal-section.png]
{title=Physical h-zero-l reciprocal section and its first Brillouin-zone boundary}
{description=Original Wigner-Seitz construction using the actual reciprocal lengths. Filled points satisfy h plus l even; open boundary points assist the construction outside the strict requested index window. The hexagon is the section of the three-dimensional first zone.}
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