PowerShell takes an interesting approach in that it accepts any truncated variant of a long-form flag as a short form, provided it isn't ambiguous (i.e. if the interpreter can't decide which long-form flag to expand a short-form flag to.)

For example, if a command features a "-ConfigFile" flag, valid short-form variants include "-C", "-Co", "-Con", "-Conf", and so on. But if the command featured an additional flag "-ConfigURL" for example, the aforementioned short-form flags would be ambiguous.