1.1 Basic node, edge, and layer properties
  1.1.1 Node and layer activity
  1.1.2 Layer aggregation
  1.1.3 Node degree, participation coefficient, cartography
  1.1.4 Edge overlap, reinforcement
 1.2 Inter-layer degree correlations
  1.2.1 Node ranking
  1.2.2 Interlayer degree correlation coefficients
  1.2.3 Interlayer degree correlation functions