taglib:tagreferenceGenerates a tag reference documentation page from any tld found in ${taglib.src.dir}. The generated name for the tag reference page is tagreference-tldname.
taglib:taglibdoc Generates a tag library documentation documentation using taglibrarydoc for any tld found in ${taglib.src.dir}.
taglib:validate Validates tag classes (Are classes loadable? Are all attributes writeable? Does the type declared in the tld match the one declared in the implementing class?) for any tld found in ${taglib.src.dir}. The validation report is saved as ${maven.gen.docs}/taglibvalidation.xml.
taglib:registerRegister the generation of tag library reports.
taglib:deregisterDeregister the generation of tag library reports.
taglib:reportGenerates the tag library validation report, tldDoc documentation and tag reference pages. Note that tag reference pages are not automatically linked in the generated site: you need to add a link manually in navigation.xml with the name tagreference-tldname (for example, it will be tagreference-dummy for a tld named dummy.tld)
taglib:convert Convert tlds between different versions. The input tld is defined by taglib.tld.src (in taglib.src.dir); the converted one is saved as taglib.tld.out in taglib.output.dir. You also need to specify input/output versions using taglib.tld.src.version and taglib.tld.out.version.

If you plan to distribute a jsp 1.1 tld with your tag library you can add the taglib:convert goal as a pre or post goal:
taglib.tld.src = ${pom.artifactId}-12.tld
taglib.tld.out = ${pom.artifactId}-11.tld
taglib.tld.src.version = 1.2
taglib.tld.out.version = 1.1
<postGoal name="java:jar-resources">
        <attainGoal name="taglib:convert" />
You can also use this goal for a one-shot conversion by setting required properties on the command line: