code: function() {
  		var flags6 = this.header[6];
  		this.mirroring = ( flags6 & 0x1 ) ? VERTICAL : HORIZONTAL;
  		this.battery = ( flags6 & 0x2 );
  		this.trainer = ( flags6 & 0x4 );
  		this.mirroring = ( flags6 & 0x8 ) ? FOUR_SCREEN : this.mirroring;
  		
  		var flags7 = this.header[7];
  		this.vs = (flags7 & 0x1);
  
  		this.mapper = (
  			(( flags6 & 0xf0 ) >> 4) |
  			( flags7 & 0xf0 )
  		);
  		
  		this.pal = (this.header[9] & 0x1);
  	}
docs: Init header flags.