The <plugin> element has the following attributes:
name – The name of the plug-in. The name attribute has a maximum length of 64. Plug-in names follow a structure similar to com.sun.solaris.
version – The version of the plug-in. Version numbers follow the standard x.y (major.minor) format.
previousversion (optional) – The version of this plug-in expected to be on the system. If not specified, an initial install is assumed. If specified, the value represents the version from which the plug-in is to be upgraded.
xmlns:xsi – Required value: http://www.w3.org/2001/XMLSchema-instance.
xsi:schemaLocation (optional) – Recommended value: http://www.sun.com/schema/SPS plugin.xsd.
schemaVersion – The version of the plug-in XML schema being used. The only value currently permitted is 5.0.