<!ELEMENT requires (name, version*)>
This element occurs in : Element: <packageinfo>
See also : Element: <name> | Element: <version>
The element requires denotes a dependency between two packages. The package containing the requires element depends on the package whose name is contained in the name sub-element.
The actual name is put into a name element because we might want to add a version in a future version.
Refer to Element: <packageinfo> for an example.