Can I enter a negative number on certain events? For instance, can I enter a negative amount to "award" in order to charge users credits for creating a new thread? Under the interest event, can I enter a negative interest level to subtract credits on a recurring basis? Or under salary, enter a negative number to subtract a flat number of credits? I'll be awarding credits for logins, uploads, etc. and want to be able to subtract credits for creating request threads and on a recurring basis to prevent hoarding and encourage credit use.