This is a wizard-specific rule.
Wizrule #6 -- Disk usage
Your directory is not very personal. This means that you should not place things you consider confidential there. Also, it's not your private storage space. Don't waste disk space on non-MUD related files, as that would occupy space Viking needs for other purposes. Non-MUD related files, such as large tar/arj/zip archives, pictures etc., may be deleted without notice before the space is needed by an arch wizard.