[en] Isomorphic symmetry reductions are a special class of klassengleiche symmetry reductions where the subgroup has the same space group type. The present contribution highlights five different isomorphic transitions of index 5 (i5), all from I 4/m to I 4/m. These superstructure formations allow (i) atom ordering in MoNi${}_4$, (ii) vacancy ordering in Nb${}_4$N${}_5$, K${}_x$Fe${}_{2-<!--\; ???\; -->y}$Se${}_2$ and Nd${}_{10}$Au${}_3$As${}_8$O${}_{10}$ and (iii) charge ordering in CsInCl${}_3$ (≡Cs${}_2$In${}^I$In${}^{III}$Cl${}_6$). The group-subgroup schemes in the Bärnighausen formalism are discussed along with the crystal chemical consequences.