The interact key is overused for far too many actions in Payday 2 these days. One press of the F key can mark a special, yell at a cop, dominate a cop, tell a bot to drop a bag, tell a bot to come to you, yell a civilian, call a teammate to you, it's a mess. With this mod, you can handle one of those functions (marking specials) just by damaging them, which also skips the step of an additional button press. Some notes:
The mod takes perks and skills into account when marking. So, with aced High Value Target, a bodyshot on a distant Sniper will mark him and cause subsequent hits to deal additional damage. Without that skill, he will be out of range, just like with normal marking.
The mod will not mark an enemy who is already marked.
The mod takes into consideration the interaction cooldown, meaning you can't shoot a million Shields and mark all of them.
Damaging enemies with explosives will not work, since this would allow you to mark enemies from around corners and whom you otherwise wouldn't be able to see.
If your attack will kill the special, it will not be marked.