An official who takes the position of another official is usually called a substitute, reserve, or replacement official.
the library
you gain another layer of security.
Senator Evan stood by the official stance of the government. The official double checked the rules. Official registration is required. Homer read the official rules.
The stymie rule was removed from the official rules of golf in 1952. Before this rule was removed a golf player would need to have to play around another ball in play even if they caused an obstruction.
The link has the official rules for the NBA.
You can find any ruling in the Official MLB Rules. These rules are available for download at the official MLB website.
In official pool rules, scratching occurs when the cue ball is pocketed or fails to hit any other ball. When scratching, the opponent gets ball in hand, allowing them to place the cue ball anywhere on the table for their next shot.
In the official rules, a deck can have up to 4 EX cards.
One can find official Blackjack rules on a number of webpages. Wikipedia, hit or stand, BlackjackInfo and Blackjack21 are few examples of online pages where one can find official Blackjack rules.
The umpire is the person that rules on plays.
Monarchy
The official ML Official rules describe the "Mobile Legends: Bang Bang" game client as the main piece of equipment needed to participate in the MLBB tournaments.