  Directional media, such as nematic liquid crystals and ferromagnets, are
characterized by their topologically stabilized defects in directional order.
In nematics, boundary conditions and surface-treated inclusions often create
complex structures, which are difficult to classify. Topological charge of
point defects in nematics has ambiguously defined sign and its additivity
cannot be ensured when defects are observed separately. We demonstrate how the
topological charge of complex defect structures can be determined by
identifying and counting parts of the texture that satisfy simple geometric
rules. We introduce a parameter called the defect rank and show that it
corresponds to what is intuitively perceived as a point charge based on the
properties of the director field. Finally, we discuss the role of free energy
constraints in validity of the classification with the defect rank.
