  Recent superconducting gap classifications based on space group symmetry have
revealed nontrivial gap structures that were not shown by point group symmetry.
First, we review a comprehensive classification of symmetry-protected line
nodes within the range of centrosymmetric space groups. Next, we show an
additional constraint; line nodes peculiar to nonsymmorphic systems appear only
for primitive or orthorhombic base-centered Bravais lattice. Then, we list
useful classification tables of 59 primitive or orthorhombic base-centered
space groups for the superconducting gap structures. Furthermore, our gap
classification reveals the $j_z$-dependent point nodes (gap opening) appearing
on a 3- or 6-fold axis, which means that the presence (absence) of point nodes
depends on the Bloch-state angular momentum $j_z$. We suggest that this unusual
gap structure is realized in a heavy-fermion superconductor UPt$_3$, using a
group-theoretical analysis and a numerical calculation. The calculation
demonstrates that a Bloch phase contributes to $j_z$ as effective orbital
angular momentum by site permutation. We also discuss superconducting gap
structures in MoS$_2$, SrPtAs, UBe$_{13}$, and PrOs$_4$Sb$_{12}$.
