dof_0 dof_1 ... are the degrees of freedom (unknowns) at the node with number index. The total number and type of the unknowns depends on the initialization part. Each node has the same unknowns.
Unknowns like pressure, temperature, etc. are primary unknowns. The other unknowns, space derivatives and the time derivative, are not primary unknowns. In the example below, -temp is 1., -xtemp is 0.2 and -ttemp is 0.1 in node 6
node_dof 6 1.0 0.2 0.1
Default all values in the node_dof records are set zero at the start of the calculation. See also: dof_label and post_point.