  The definition of index for differential algebraic equations (DAEs) or
integral algebraic equations (IAEs) in the linear case (time variable) depends
only on the coefficients of integrals or differential operators and the
coefficients of the unknown functions. Is this possible for the nonlinear case?
In this paper we answer this question. In this paper, we generalize the index
notion for the nonlinear case. One of the difficulties for nonlinear case, is
its dependence on the exact solution which motivates us to give an important
warning to whom want to solve DAEs using numerical methods such as Runge-Kutta,
multistep or collocation methods.
