[numthreads(8,8,1)]
void main(uint3 tid : SV_DispatchThreadID )
{
}

[numTHreaDs(4,4,2)]  // case insensitive
void main_aux1(uint3 tid : SV_DispatchThreadID )
{
}

[numthreads(1,4,8)]
void main_aux2(uint3 tid : SV_DispatchThreadID );