c – 为什么我应该使用1位位域而不是布尔？

UCLASS(abstract,config=Game,BlueprintType,hidecategories=("Pawn|Character|InternalEvents"))
class ENGINE_API ACharacter : public APawn
{
    GENERATED_UCLASS_BODY() 
...
    UPROPERTY(Transient)
    uint32 bClientWasFalling:1; 

    /** If server disagrees with root motion track position,client has to resimulate root motion from last AckedMove. */
    UPROPERTY(Transient)
    uint32 bClientResimulateRootMotion:1;

    /** Disable simulated gravity (set when character encroaches geometry on client,to keep him from falling through floors) */
    UPROPERTY()
    uint32 bSimGravityDisabled:1;

    /** 
     * Jump key Held Time.
     * This is the time that the player has held the jump key,in seconds.
     */
    UPROPERTY(Transient,BlueprintReadOnly,VisibleInstanceOnly,Category=Character)
    float JumpKeyHoldTime;

上面的代码来自UE4.他们似乎使用uint32一位bitfield而不是bools.他们为什么要这样做？