\item$H(n)$ is the number of hits in the histogram for bin $n$.
\item$H(n)$ is the number of hits in the histogram at output $n$. A hit at output $n$ means that the signal propagated down to output $n$, without reaching output $n-1$.
\item$W(n)$ is the width of bin $n$.
\item$C =\displaystyle\sum\limits_{n} H(n)$ is the total number of hits in the histogram.
\item$R(n)$ is the time stamp of an event whose signal propagated up to bin $n$. The LUT contains the function $R$.
\item$C =\displaystyle\sum\limits_{n=0}^{N-1} H(n)$ is the total number of hits in the histogram.
\item$R(n)$ is the time stamp of an event whose signal propagated down to output $n$ (without reaching output $n-1$), measured backwards from the clock tick.
\item$f$ (respectively $f_{0}$) is the current (respectively reference) frequency of the online calibration ring oscillator.