  In this paper, we discuss differentiation of solutions to the boundary value
problem $y^{(n)} = f(x, y, y^{'}, y^{''}, \ldots, y^{(n-1)}), \; a<x<b,\;
y^{(i)}(x_j) = y_{ij},\; 0\leq i \leq m_j, \; 1 \leq j \leq k-1$, and
$y^{(i)}(x_k) + \int_c^d p y(x)\;dx = y_{ik}, \;0 \leq i \leq
m_k,\;\sum_{i=1}^km_i=n$ with respect to the boundary data. We show that under
certain conditions, partial derivatives of the solution $y(x)$ of the boundary
value problem with respect to the various boundary data exist and solve the
associated variational equation along $y(x)$.
