2.9.  os.properties

The os.properties task creates some Ant variables providing information about name, type, architecture and version of the underlying operating system.

In general you may eval this information using the properties provided by java.lang.System.getProperty( name). But the clou is that os.properties creates Ant properties DEPENDING of the underlying operating system. If the task is executed on Windows a property os.family.windows will be created for example.
By having such a tagging property you can easily configure your Ant file to execute a target depending on the underlying platform.

os.properties takes no attributes.