Object Iconography

There are a variety of symbols that appear in stocks, converters and flows to indicate specifics about that object and the states it is in. Some of the annotations can appear in combination. For completeness we first list the types of building blocks and then the additional annotations.

Symbol Description
Non-negative Stock. A stock that can't go negative (the outflows will be constrained to prevent this from happening). See also non-passthru below.
Stock. The in the lower right hand corner indicates that a stock can go negative (this mark only appears in Model . mode not in Map mode). To set this right click on the stock or uncheck non-negative in the Properties panel. Checking non-negative removes the mark.
Conveyor. A stock that hold material for a set amount of time before it flows out. There can also be leakages.
Queue. A stock that keeps incoming material in order and then dispatches it to downstream stocks based on their ability to take new material.
Non pass-thru Queue. As above, but outflows are computed with the assumption that inflows are 0 (see also non-pass-thru below).
Oven. A stock that takes material, then holds it for a time, blocking new material from coming in, before releasing it.

Cloud. A source or sink for content moving through a flow. The cloud is essentially a stock that is outside the boundary of the model and therefore not computed.

 
Converter. A variable that is used to hold intermediate computations.
Delay Converter. A converter that delays the inputs and therefore has many characteristics of a stock. There are a variety of delaying builtins, but SMTH1 and DELAY are the most common.
Summing Converter. A converter that adds its inputs without the needs to connectors coming into the converter. This is a diagrammatic convenience to help prevent clutter.
Pathway Score. A converter reports the (raw) pathway score as computed for Loops that Matter.
Loop Score. A converter reports the (normalized) loop score as computed for Loops that Matter. Computed values are available only after a simulation completes and can not be used in other variables.
Flow. A flow, between two stocks, from a cloud to a stock, or from a stock to a cloud. Material can only flow in the direction of the arrow. If the computation of the flow value is negative the flow will be 0.
Biflow. A flow that moves material in the direction of the solid arrow, but that can also take on negative values effectively taking away material from the downstream stock. The dashed arrowhead indicates that material will be taken away, when the flow value is positive.
Leakage. Indicates the flow represents leakage from a conveyor. The second and additional outflows from a conveyor are automatically marked as leakages.
Unit Converting Flow. This changes the units of measure, between the upstream and downstream stocks. For example, you could have an outflow in kilograms adding to a stock measured in grams.
Connector. An indication that the starting variable (on the left in this case) is used when computing the ending variable. Connector can only go into flows, converters, and modules.
Information Connector. An annotation convention to indicate that the connector conveys information (as opposed to action and consequence). The visual distinction does not affect computation.
Connector with delay and polarity. Connectors can be annotated to indicate which direction the end variable change in response to an increase in the start variable and whether the response is delayed. The visual distinction does not affect computation.

Module. A module contains a submodel. You can connect modules (using connectors) to indicate that variables in one are used in another.
Sector. A sector is a convenience container to allow grouping of variables. It can be locked (click on the padlock) to keep everything inside of it together if it is moved.
Placeholder. A Placeholder contains a list of possible variables. They can be used in tables and graphs on the model and interface and allow simple switching between variables without requiring multiple graphs.
Graph. When you minimize a graph by clicking on the button an icon for it will be displayed. Double click on the icon to restore the graph.
Table. When you minimize a table by clicking on the button an icon for it will be displayed. Double click on the icon to restore the table.

Numeric displays and all of the interface objects are displayed in a manner to convey information. They are not icons as such, though there are icons used in the creation toolbar to indicate which object you are choosing (see Interface Build Toolbar).

Additional Annotations

Symbol Description
indicates that the flow or converter is a graphical function.
Variables that are arrayed are drawn to indicate that each icon represents multiple values. The way these are drawn depends only on whether the variable is arrayed or not, it does not change based on the number of dimensions or the size of those dimensions.
non pass-thru. The in the lower right hand corner indicates that the stock has inflows dependent on its outflows (possibly through a long chain) and will therefore constrain outflows before the inflows are known. This is likely to result in positive stock values even when outflows are constrained. Mark a stock as can-go-negative to remove this behavior. (Only visible in model mode.)
Stella live knob - indicates that the variable's equation is a constant and can be changed by dragging (pressing the mouse button down and moving the mouse) on the knob. This occurs on the model when in explore mode and the knob disappears when in Edit mode. As you change the value an arrow will appear indicating the direction of change.
Indicates the value for that variable being use is something other than the equation. Instead the variable is controlled by an input device, a Stella live change, the Parameter Control dialog, or data import. Restore all devices will remove the symbol except for those resulting from data imports, which will remain while the import is active.
Indicates that the value for the variable has been imported from an outside source. The x will remain until the import link is deactivated, or the variable is removed from the file referenced by the link. If the import link is set to control variables the control variable symbol () will also appear.
indicates the variable has no equation or the equation is invalid. This is displayed when the model in is model () mode. It will not be displayed in map () mode.
Indicates the variable is a ghost of another variable in the same module. You can create a ghost using the tool.
Indicates the variable is marked to accept input from another variable in a different module, but has not yet been connected to another variable.
Indicates the variable is a cross level ghost of another variable in a different module (accepts input and has been assigned). You can also create a cross-level ghost using the tool.

The dashed line inside of the circle or rectangle indicates that the variable can provide (but is not providing) output to (be the source of a cross level link for) a variable in another module.

The solid line inside of the circle or rectangle indicates that the variable does provide output to (is the source of a cross level link for) a variable in another module.

Stamped Flow. For cycle time models this flow is marked stamped and will provide (or replace) a time stamp for material flowing through. Downstream flows can then be used to determine residence time and other characteristics of the material after it has been processed.

Cycle Time measurement variable. This variable uses one of the cycle time builtins to measure characteristics of the material flowing out of stocks (such as how long it took to process).

Locked Module. A locked module is password protected. You can simulate the model without unlocking but in order to look inside of it the password must be provided.