8.8 Constraining Time-Dependent Properties to Facilitate Time-Based Analysis 195 of all the powered devices into one collection for binding to the component demands parameter of demand equation. 8.7 CAPTURING VALUES IN BLOCK CONFIGURATIONS To allow an analysis tool to evaluate blocks containing constraint properties, at least some of the value properties of the block under analysis need to have specific values defined. Often, these values are provided during analysis through the interface of the analysis tool, but they can also be specified using a block configuration. This is done by creating either a specialization of the block with the required initial values, or by using an instance specification to describe an instance of the block. Although the block in Figure 8.7 contains all the relationships required to perform an analysis of the Mechanical Power Subsystem block, the related properties do not have values, and so there is little scope for analysis. Figure 8.8 shows a configuration of the Mechanical Power Subsystem block, specified as a specialization of the original block and called Mechanical Power Subsystem with 2 W and 0.4 W motors. Even though there are no mandatory naming standards for configurations, it is often useful to include information about the configuration, as part of its name. Note that, in this case, all the values for the related properties are shown and so the demand equation constraint property simply acts as