The phrase "nomination slots" refers to available positions or opportunities for someone to be selected as a candidate for a particular position or award. Full definition
It has an outside shot for Best Picture — easier if there were a solid ten, harder with only five nomination slots for voters to fill in. (awardsdaily.com)
With 2018 marking the 90th annual Academy Awards, that means the Academy of Motion Picture Arts and Sciences has only recognized four women among a possible 437 total nomination slots, or 0.009 percent. (etonline.com)
The fighting genre can't even muster up enough nominees to fill out its category this year, although there has been a late call for Nitroplus Blasterz by more esteemed media from the games press this week, following an empty nomination slot. (pauseresume.com)