In the previous chapter, we looked at several components that are included in the FormulaForce package. These have all been exposed for use by tools and developers' code in the subscriber org through the global access level.
When developers consume these components inside their own component, there is a facility through the bundle metadata for them to express what package version they want the platform to assume when their code interacts with the packaged component. This allows the definition and behavior versioning of your components. If this information is not present, the currently installed package version is assumed.
System.requestVersion, {!Version}, and cmp.getVersion() are available to determine the version your component needs to honor in Apex or JavaScript.