with species and broadener. In any case there are not individual values for every molecular line and often parameters have only been measured or calculated for a small fraction of transitions. Therefore, rather than pre-determine values for every molecular line and increase the size of the line lists, which are very large for some molecules, a separate pressure broadening parameters file is provided. This file contains three types of parameters: experimental, theoretical and semi-empirical. Experimental, theoretical and semi-empirical parameters from the literature are presented with their respective full or partial quantum number assignments. Additional semi-empirical parameters are determined by compiling all experimental and theoretical parameters as a function of $J{^{\prime\prime}}$, the total rotational quantum number of the lower level of the transition, and computing an average value for each $J{^{\prime\prime}}$. To avoid introducing additional error, no extrapolation is attempted beyond the $J{^{\prime\prime}}_{\rm max}$ for which data are available, the parameters are simply assumed to be constant from this point. This is a very basic model similar to that used by other line-width studies [@97BuMaHu.broad; @jt483; @14AmBaTr.broad]. Constructing the pressure broadening parameters file in this way ensures that parameters are provided for every spectral line. Table \[tab:broad\_ref\] lists the main sources 