code: function BlockMap() {
  
    if( !(this instanceof BlockMap) )
      return new BlockMap()
  
    this.signature = 0x00000000
    this.version = 0x00000000
    this.sectorNumber = 0x0000000000000000
    this.sectorCount = 0x0000000000000000
    this.dataOffset = 0x0000000000000000
    this.buffersNeeded = 0x00000000
    this.blockDescriptorCount = 0x00000000
    this.reserved1 = 0x00000000
    this.reserved2 = 0x00000000
    this.reserved3 = 0x00000000
    this.reserved4 = 0x00000000
    this.reserved5 = 0x00000000
    this.reserved6 = 0x00000000
    this.checksum = new UDIF.Checksum()
    this.blockCount = 0x00000000
    this.blocks = []
  
  }
docs: BlockMap (BLKX) data (aka Mish Data)
  @constructor
  @memberOf UDIF
  @return {BlockMap}