STOMP-EOR is designed to solve problems involving the transport of energy, water, CO2, CH4, salt, and a user-defined number of petroleum components with passive solutes or reactive species through variably saturated geologic media under non-isothermal conditions. Alternatively under the black-oil option, the simulator solves problems involving the transport of water, oil, gas, and salt passive solutes or reactive species through variably saturated geologic media under isothermal conditions. The Initial Conditions Card for this operational mode is used to specify the state of the system at the start of the simulation. For STOMP-EOR the number of degrees of freedom depends on the initial phase condition: 1) aqueous saturated (IC1), 2) aqueous partially saturated (IC2), or 3) aqueous unsaturated (IC3). A phase condition must be specified for every grid cell, and each phase condition has a prescribed number of input parameters, which must be defined. Solutes are passive tracers that partition between the three mobile (i.e., aqueous, nonaqueous-liquid and gas) phases and the immobile solid phase (i.e., geologic media). When solute transport is specified the initial concentrations of solutes are defined via the solute variable options. Species are reactive tracers that are associated with a single mobile phase (i.e., aqueous, nonaqueous-liquid, or gas) or the immobile solid phase (i.e., geologic media). Species migrate between phases via defined equilibrium or kinetic reactions. When reactive transport is specified and the ECKEChem module is implemented, the initial concentrations of species are defined via the species variable options. There are three types of parameters, whose initial conditions can be specified: 1) state variables, 2) solute variables, and 3) species variables. A number of options are available for specifying parameters.