As Microsoft neither documented all partition types already assigned by them nor wanted to maintain foreign assignments, third parties started to simply assign partition types on their own behalf in a mostly uncoordinated trial-and-error manner. When the market of PC operating systems and disk tools grew and liberated, other vendors had a need to assign special partition types to their products as well. Lists of assigned partition types to be used in the partition table in the MBR were originally maintained by IBM and Microsoft internally.