Explanation/Reference:
C: Alias names, or aliases, are intended to provide a more user-friendly means of referring to Oracle ASM files, rather than using the system-generated filenames.
You can create an alias for a file when you create it in the database, or you can add an alias to an existing file using the ADD ALIAS clause of the ALTER DISKGROUP statement. You can create an alias in any system-generated or user-created Oracle ASM directory. An alias must include the disk group name; you cannot create an alias at the root level (+).