Systems comprised of component manufacturer/models are defined and analyzed via the System Builder, which is activated by selecting the System Analysis Level option from the Analysis Level menu on the Main Screen and then clicking the System Builder button.

System Definition
System definition begins by clicking the New System button at the bottom of the System Builder Screen. This clears any system information that may be present and sets the focus on the System ID box. Identifying information for the system are entered in the text boxes at the top of the screen. Most of the identifying fields are self-evident. The System Rel Target is applicable only if there is some desired overall reliability for the system of interest.
 
Defining a system also involves identifying component items within the IntervalMAX database.  The search for system components may be initiated at the Class, Group, Manufacturer/Model or Serial Number level. The level at which to begin the search for a component is set via the Starting Level menu.
 
A list of items that can be added to as a system components is be viewed by clicking the Show Candidates menu. If the Class Level option is selected on the Starting Level menu, for example, the Candidates List will display existing Instrument Classes. Alternatively, if the Group Level option is selected, the Candidates List will display existing Groups. Other options are the Model Level and the Serial Number Level. Selecting the Model Level displays manufacturer/models in the Candidates List, while selecting the Serial Number Level displays individual items of equipment.
 
System components may be manufacturer/models or specific Serial Numbered items. Getting to specific model numbers within a Class or Similar Equipment grouping involves double-clicking listed items until the model number level is reached. Getting to specific serial numbers within a Class, Similar Equipment or Manufacturer/Model grouping involves double-clicking listed items until the serial number level is reached.
 
Components are added to a system by dragging them from the Candidates List onto the Components List. Once a component has been added to the Components List, the Candidates List must be closed and then re-opened. The Candidates List is closed by clicking the Hide Candidates menu.
 
The reliability target for a system component reflects the criticality and demand for the component as a member of the system. Accordingly, the reliability target of an item as a system component may not be the same as the target for the item when used as a stand-alone instrument. Modifying the reliability target for a component is done by entering the desired target in the Rel Target field of the Components List.

A system component is deleted by clicking the component in the Components List and click the Remove Component button.  A component is replaced by first deleting it and then adding the new component, as described above.  An entire system can be deleted by clicking the Delete System button.
 
Recall Options

A variety of system and component recall options are available for managing component calibrations. In some cases, the desired combination of options may be predetermined. In others, it may be worthwhile to experiment with different options to establish the most cost-effective recall strategy consistent with reliability objectives. Certain combinations of options disable the System Rel Target input at the top of the screen.
 
System Recall options that relate to setting intervals for the system as a whole are as follows: Cal to Meet System Target - this option is selected if it is desired that the system as a whole meet a specified reliability target. Cal at Shortest Interval - this option exercises Ferling's Method for setting system calibration intervals to meet component reliability requirements without compromising system reliability. No System Recall - this option is selected if there is no requirement to recall the system as a whole for calibration.
 
Component Recall options include: Cal as Stand-Alone - this option is selected if there is no requirement to synchronize or otherwise interrelate component recall schedules. Stratify Calibrations - this option allows the system to be recalled at a given calibration intervals while holding components to individual calibration intervals.  Thus, although all components are recalled at each system calibration, only those components due for calibration are serviced.  Cal at System Interval - this option is selected in cases where each component is calibrated at the system recall interval. Selecting this option in conjunction with the Cal at Shortest Interval system recall option implements Ferling's Method.
 

Computed System Reliability and Interval
The System Builder computes reliabilities for components and also computes a System Reliability for the system as a whole. Also computed are a System Interval, if appropriate, lowest and highest component reliabilities and lowest and highest component intervals. Typically, the best combination of Recall Options produces the highest System Reliability and the longest System Interval.