When using entities from domains in a Rulesheet, it is important to ensure uniqueness, which means aliases must be used to distinguish one entity from another.
Figure 31. Non-unique Entity names prior to defining Aliases
In Non-unique Entity names prior to defining Aliases, both Aircraft entities have been dropped into the Scope section of the Rulesheet. But because their names are not unique, an error icon appears. Also, the fully qualified domain name has been added after each to distinguish them. By fully qualified, we mean the ::US_Fleet:: designator that follows the first Aircraft and ::WW_Fleet:: that follows the second.
But it would be inconvenient (and ugly) to use these fully qualified names in Rulesheet expressions. So we require that you define a unique alias for each. The aliases will be used in the Rulesheet expressions, as shown in Non-unique Entity names after defining Aliases.
Figure 32. Non-unique Entity names after defining Aliases
appears. Also, the fully qualified domain name has been added after each to distinguish them. By fully qualified, we mean the ::US_Fleet:: designator that follows the first Aircraft and ::WW_Fleet:: that follows the second.