The plugin version is detected by PluginDetect.getVersion('Flash'). The getVersion() method will return a value of either null or a string of 4 numbers "A,B,C,D" separated by a comma. Each of these 4 numbers is an integer >=0.
In some older browsers, only the first 3 numbers of the plugin version are detectable. Hence the plugin version would appear as "A,B,C,0".
Otherwise, all 4 numbers should be detected to give us a plugin version of "A,B,C,D".