hhline – Better horizontal lines in tabulars and arrays

The com­mand \hh­line pro­duces a line like \hline, or a dou­ble line like \hline\hline, ex­cept for its in­ter­ac­tion with ver­ti­cal lines. The com­mand takes a pream­ble (rather like the pream­ble of a tab­u­lar en­vi­ron­ment), and this spec­i­fies whether there are to be one or two hor­i­zon­tal lines, and what hap­pens when the hor­i­zon­tal line meets a ver­ti­cal one.
The pack­age is part of the tools bun­dle in the LaTeX re­quired dis­tri­bu­tion.