IN  PPREFIX_TABLE PrefixTable,
  IN  PSTRING FullName

Routine Description:

    This routine finds if a full name has a prefix in a prefix table.
    It returns a pointer to the largest proper prefix found if one exists.


    PrefixTable - Supplies the prefix table to search

    FullString - Supplies the name to search for

Return Value:

    PPREFIX_TABLE_ENTRY - a pointer to the longest prefix found if one
        exists, and NULL otherwise