Code is using wrong function names

I confirm this error.

The function definition in opensearch.module is "opensearch_check_plain", sans the initial underscore, as the name.

Patching this module by changing the function definition resolves the issue.

The current recomended code in Drupal Modules is the wrong 6.x-1.3 which is unusable. I suggest to backport changes in 6.x-1.4-beta1 or consider this version as the stable one.

The current behaviour of this module is broken as is.

I fully agree with @lord_atreide - having downloaded and then turn on the module (version 1.3 'stable') to be confronted with a fundamental PHP error, is just plain wrong.

The 1.4 beta1 release needs to be on the modules homepage as stable (why not call it 1.4?)

It is not possible to port the fix that is present in version 6.x-1.4-beta1 to a pre-existing version; this is how Drupal release system works.

@kiamlaluno but you can release a new stable version so that users are not confronted with a PHP error!

@wiifm: You can download it yourself at http://drupal.org/node/925690. Because the 6.x-1.4 version is still beta, our release system doesn't show it on the project frontpage.