Can someone explain this line of the rules to me without double negatives?

"Manual Mashing, not holding the Wrist Protector key (C/Ctrl) and mashing Z/Enter faster than 15 textboxes per second (for significant lengths of time), is banned."

Thanks

The in-game wrist protector (holding C/CTRL) mashes at 15 textboxes per second (TBPS).

You could theoretically mash faster than 15 TBPS by using Enter and Z alone without wrist protector. The problem with this is that it is damaging to your wrists long term.

To discourage runners from damaging their wrists for good times, this rule was implemented, so that every runner should use wrist protector for mashing textboxes. This means that you are not allowed to manual mash faster than 15 TBPS.

This rule is for all chapters, ch3, and ch4.

I believe that is everything for this rule for all the new categories.

thanks

just to confirm, this means that holding the wrist protector key is essentially mandatory.

Yes.