underscore – Control the behaviour of "_" in text

With the pack­age, \_ in text mode (i.e., \tex­tun­der­score) prints an un­der­score so that hy­phen­ation of words ei­ther side of it is not af­fected; a pack­age op­tion con­trols whether an ac­tual hy­phen­ation point ap­pears af­ter the un­der­score, or merely a break point.
The pack­age also ar­ranges that, while in text, ‘_’ it­self be­haves as \tex­tun­der­score (the be­haviour of _ in maths mode is not af­fected.