The parameters specifying the size of all arrays within VMODEL are contained in the file vmodel.par and may be altered to suit a particular problem and memory requirements. model layers - player points defining a single layer boundary (must be a multiple of 10) - ppcntr points at which the upper or lower layer velocity is defined (must be a multiple of 10) - ppvel 1-D velocity profiles - pnvp points defining layer boundary versus two-way travel time or RMS velocity profile - ppnpts