Local times of deterministic paths with finite variation

In this note, we define the numbers of level crossings by a c{\`a}dl{\`a}g (RCLL) real function x: [0,+∞) → R and, in analogy to the work of Bertoin and Yor [BY14] we prove that for x with locally finite total variation these numbers are densities of relevant occupation measures associated with x. Next, depending on the regularity of x and f: R → R, we derive change of variable formulas, which may be seen as analogous of the It\^o or Tanaka-Meyer formulas. Some of these formulas are present in [BY14] but we also present some generalizations.