In some web.xml I find DOCTYPE reference of "web-app_2_2.dtd",(in Weblogic 5.1 example) in others, of "web-app_2.2.dtd" (in java pet store). What is the difference between the two DTDs?

Luigi Viggiano

I believe that web-app_2.2.dtd is misspelled and you can verify it at this page: J2EETM — DTDs.

Both are aivable at Sun' site:

Maybe this is to prevent errors for misspelled web.xml like the one that you found.

I've made a diff between them and contents are identical, so no problem may occur, but it's better to make things right.