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356 Creating Flow
Flow attributes
On the other hand, if there is no upstream flow available to potentially satisfy downstream demand, the attribute values on the connectors in between will be a Blank.For example, if the demand is for Vanilla yogurt and the Tank has Vanilla yogurt but the effective rate is currently zero, the attribute value will be “Vanilla”. However, if the effective rate is zero and the demand is for Berry yogurt, which isn’t currently present in the Tank, the flow attribute value will be a Blank.
Managing and displaying flow attributes
The Flow Attributes tab of the Executive block (shown below) is for managing flow attributes – deleting, renaming, and changing their initial values. It is also where the strings for string layer attributes are defined and where you can search for blocks that use a specific flow attri- bute.
Unlike an item attribute, which is assigned to individual items, flow attributes are assigned to the flow in a section of a model. Flow attribute values can thus be read at any time and from any model location. Each Rate block that holds or provides flow has a Contents tab showing the attribute values of its flow by volume. The Get(R) block can be used to retrieve the values of flow attributes elsewhere in the model.
In order to manipulate flow based on the attribute, usually to route it or pro- cess it, you need to get the flow’s attribute value. The most common method for getting attributes is to select the attribute by name from the list in the attribute popup menu in the Get(R) block, as shown on right. When flow passes through the Get(R) block, the block accesses information about the attributes that have been specified in the table in its dialog. It then reports the information in the
Discrete Rate

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