Boundary triples for integral systems on finite intervals

Let P, Q, and W be real functions of bounded variation on [0, l], and let W be nondecreasing. The integral system $$ J\overrightarrow{f}(x)-J\overrightarrow{a}=\underset{0}{\overset{x}{\int }}\left(\begin{array}{cc}\uplambda dW- dQ& 0\\ {}0& dP\end{array}\right)\overrightarrow{f}(t),\kern1em J=\left(\begin{array}{cc}0& -1\\ {}1& 0\end{array}\right) $$ (0.1)