Security Rules

If you write rules on your TM1 security cubes be careful they don't become invalid.
e.g. You write a rule for a specific security group to have read permissions but 6 months later you decide to delete that group.

If you don't delete that rule the next time your server re-starts, it will find that rule file to be invalid and not apply any rules, thus you risk security profiles not working until the rule file is updated.

XRU Files Tip

I find TM1 Rule worksheets (XRUs) as the best place to write my rule files.
They allow for easy formatting and commenting for your rules.
One other advantage is that you can keep backups of your rules by just copying your worksheet. This allows you to change your rules, test them out and if it all turns to custard, revert to the backup.
You can also have multiple worksheets within the workbook for different scenarios e.g. a rule to save for the Forecast and a rule to save for Budget time.