Appendix 2: Sun-Supported Specification-Version and Implementation-Version Formats

Specification-Version and Implementation-Version follow these rules for Sun products, and third-party products must follow the same rules for Java Plug-in to make reliable decisions about whether an extension is up-to-date or not:

The Specification-Version string will be of the form:


where n1, n2, and n3 are integers, n1.n2 is the major version number, and optional n3 is the minor version number (also referred to as the maintenance version number).

The Implementation-Version will be of the same form initially but may:

Both patch version number and milestone name may not be used together in the Implemenation-Version string.

The general form is as follows:


Integers (n1,n2, n3 ...), letters, dots, hyphens, and underscores , may be used in the version format as described above; no other characters ("*", "+" ...) are allowed.

Note that the Specification-Version and Implementation-Version numbers are in theory independent, though in practice they are often in sync with each other.


Specification-Version examples: 1.3, 1.4

Implementation-Version examples: 1.3.1, 1.4.0_02, 1.4.0-beta3

While these are the rules, it is always a good idea when using a third-party extension JAR to examine its MANIFEST.MF file to see what actual values are in it. If it does not follow these rules, you may need to change your applet JAR MANIFEST.MF accordingly or alter the extension JAR.