page-months (one page=4096 bytes) Terminal or network connect time-charged in minutes Cards read and punched-charged by the card Paper tape punched-charged by the foot Tapes mounted and tape drive usage time-charged by number of tapes mounted and minutes of usage Program product surcharges (charged on a program by program basis for certain licensed program products) Other resources (e.g. plotters, photo-typesetters, etc.) Note that while there is a charge for virtual memory used, there is no charge for real memory used. Note too that there is no change for page-in operations, although they are included in the session summary information that is reported at sign off. Different rates can be changed for different classes of projects (internal, external, commercial, ...) and for different times of the day or days of the week. Depending on the policies and practices at different sites, charges can be for "real money" or "soft money" (soft money is sometimes called "funny money", although just how funny it is usually depends on who is or isn't paying the bills). Users can display the cost of a session using the $DISPLAY COST command, can display their account balances using the $ACCOUNTING command, and the costs of a session and the account's remaining balance are displayed when the job or session ends. There is also an option ($SET COST=ON) that will cause the incremental and cumulative session cost to be displayed after each MTS command is executed. To prevent a user from overdrawing their account, the money limit is checked when the user attempts to sign on. If the account balance is zero or negative, the sign on is not allowed. For batch jobs, if the account balance is not sufficient to cover the charges estimated for the job, the job is not run. For terminal sessions, when an account's balance falls below one dollar, a warning "You have run out of money" followed by the current balance is printed. This "out of money" message is repeated at regular intervals until the user signs off. Signon IDs can run a negative balance, but usually not a large one or by accident. Depending on the administrative policies at a particular site, projects often have to pay for resources used even if they are beyond the amount authorized. To provide additional protection against accidents that might quickly use more resources than desired, users may also set global and local limits on