The dc optimal power flow is a linearized optimization of the grid state. It offers two cost function options, that are fitting special use cases. To understand the usage, the OPF tutorial is recommended (see tutorial).
pandapower.rundcopp
Flexibilities, costs and constraints (except voltage constraints) are handled as in the opf. Voltage constraints are not considered in the DC OPF, since voltage magnitutes are not part of the linearized power flow equations.
Note
If you are interested in the pypower casefile that pandapower is using for power flow, you can find it in net["_ppc_opf"]. However all necessary informations are written into the pandpower format net, so the pandapower user should not usually have to deal with pypower.