This is a space of vector valued Siegel modular forms with real representation $\mathrm{Det}^{ 34}\otimes\mathrm{Sym}^{ 0 }$. The following table gives the dimensions of various subspaces of $M_{34, 0}(\mathrm{Sp}(4, \mathbb{Z}))$.

Total14
Eisenstein1
Klingen2
Maass5
Interesting6

The following samples live in this space.

34_E   34_Klingen   34_Maass   34_Ups