Why Cant we create a folder with name CON, com1, com2, com3, com4, com5, com6, com7, com8, com9, lpt1, lpt2, lpt3, lpt4, lpt5, lpt6, lpt7, lpt8, lpt9, con, nul, and prn...

When I try to create any Folder with these name... com1, com2, com3, com4, com5, com6, com7, com8, com9, lpt1, lpt2, lpt3, lpt4, lpt5, lpt6, lpt7, lpt8, lpt9, con, nul, and prn
it automatically renames to New Folder, Why? can any one tell me.