Each asset type typically has its own PM by Class Code window. Use this window to establish periodic maintenance (PM) activities for each class and when those activities are to occur. The PM activities that you establish in this window are then changed into work orders in the Work Orders from PM window and into line items in the Plan Matrix window. The amount of work that is required is calculated using the formula established in the PM Activity Amount Rules window.

There are two ways to define PM schedules:

• By inheriting PM activities from the nearest class code ancestor that has a set of PM activities assigned to it.
• By directly entering the set of PM activities, which takes precedence over inheritance.

These two processes apply to a class. You can also specify a PM schedule for a particular inventory item by using the PM by Inventory window to override the PM schedule established for the class to which the inventory item belongs.

The PM by Class Code window contains two panes: Class Codes and PM Schedule.

Class Codes Pane

The left pane, Class Codes, shows a tree view of the classification codes for the asset type. A '+' sign will expand the hierarchy, while a '–' sign will contract the hierarchy. (If no sign is shown, then this node is the lowest node in the hierarchy and cannot be contracted or expanded further.)

A check mark in the square beside the name of a class code indicates that it has its own PM schedule. If the square is clear, then the class code inherits its PM schedule from its parent class code. For example, say that the Four-lane subclass had an empty square beside it, but the Two-lane subclass had a check mark in the square beside it. This indicates that the Four-lane subclass follows the PM schedule of the Primary class, while the Two-lane subclass has its own PM schedule.

When you right-click a class in the hierarchy, a shortcut menu is displayed. This shortcut menu contains the common commands along with the following special commands:

• Define Its Own PM Setup: When an inventory type follows the PM schedule of its next-highest ancestor, this command is available. When available, this command overrides the PM schedule of the inventory type that is next-highest in the hierarchy and allows you to establish a different PM schedule for the inventory type to which you pointed.
• Inherit Parent PM Setup: When an inventory type has its own PM schedule, this command is available. When available, this command removes the current PM schedule and assigns the PM schedule of the inventory type that is next highest in the hierarchy to the inventory type to which you pointed.

PM Schedule Pane

The pane on the right, PM Schedule, shows the PM activities (and when those activities are to occur) for the class selected in the Class Codes pane. What you are allowed to do in this pane depends on whether the PM schedule is for the selected class (in which case a check mark is shown in the square beside the name of the class) or is inherited from the next-highest class in the hierarchy (in which case an empty square is shown beside the name of the class):

• When the square contains a check mark, you can add, modify, or delete any of the information in the PM Schedule pane.
• When an empty square is shown, the displayed information is read-only.

In the PM Schedule pane, the Activity column shows the PM activity to be performed. The PM Trigger and PM Parameters columns specify when the activity is to occur. The triggers can be one of the following:

• Perform after defect N score is below M or after K days: This activity is performed either after a user-defined number of days ("K") have elapsed since the scheduled start date of the last occurrence of this activity or the defect score ("N") is below a user-defined threshold ("M"). After selecting this option, a dialog box is displayed to enter the defect type, the defect score threshold, and the number of days.
• Perform after N days: The activity is performed after a user-defined number of days elapses since the scheduled start date of the last maintenance activity. After selecting this trigger, a dialog box is displayed to enter the number of days.
• Perform N times on the M-th month: In these modules, this trigger sets the activity to be performed a user-defined number of times in a user-specified month. After selecting this trigger, a dialog box is displayed to enter the user-defined parameters. Both parameters are displayed as numbers in the PM Parameters column. For example, performing an activity twice in April would mean entering 2 in the Num_Times field and entering 4 in the Eff_Month field in the dialog box. This would be displayed as 2;4 in the PM Parameters column.
• Perform on defined month: The activity is performed once in the user-specified month. After selecting this trigger, a dialog box is displayed to enter the month. After entering the month (as a number) and closing the dialog box, the month is displayed as a number in the PM Parameters column.

When you right-click an activity, a shortcut menu is displayed. This menu provides the common commands along with the following special command:

• Define Argument(s): This command allows you to modify the values shown in the PM Parameters column. When this command is selected, a dialog box opens that is appropriate for the type of PM trigger. Enter the new value(s) and select OK to update when the activity is to be performed. (Note that the PM Trigger Description column will not update until you close and re-open the window or click .)