The process_comment tag is meant to be used at the successful submission of a comments form.
It simply tries to insert the submitted comment into the database. If it is successful in inserting the comment, the tag sets the k_process_comment_success variable otherwise it sets the k_process_comment_error variable in the context of its parent tag.
Please see Core Concepts - Comments for an example of this tag's usage.
This tag does not accept any parameters.
This tag is self-closing and does not set any variables of its own except the k_process_comment_success and k_process_comment_error variables that it sets in the context of the calling tag to signal the result of its operation.