Another type of grave site considered for re-use are empty plots purchased years ago but never used. In principle it would seem easier to "re-use" such grave sites as there can be no claims of desecration, but often this is made complicated by the legal rights to be buried obtained by the pre-purchase, as any limited tenure clause only takes effect after there has been a burial. Again, cemetery authorities suspect that in many cases the holders of these burial rights are probably dead and that nobody will exercise that burial right, but again some families are aware of the burial rights they possess and do intend to exercise them as and when family members die. Again the difficulty of being unable to locate the holders of these burial rights complicates the re-use of those graves.