This plugin numbers your comments sequentially and hierarchically, with full support for the new comment features available in WordPress 2.7 and later -- including threading, paging, and your choice of ascending or descending date order.
For more details on what's new in the latest main release, version 1.3, please see the update announcement: Two WordPress Plugins Updated for 2.9
The introduction of WordPress 2.7 brought with it significant new capabilities for threading and paging comments, but these same changes in WordPress mean that well established methods for numbering comments -- like including a basic incrementing counter within your template code -- no longer do the trick. Fortunately, taking advantage of modern comment handling features like paging and threading doesn't have to mean giving up comment numbering altogether.
Coupled with a new template function for displaying comments which debuted in WordPress 2.7, Greg's Threaded Comment Numbering plugin provides accurate sequential numbering for each comment, including hierarchical numbering up to the full 10 levels supported by WordPress.
The plugin numbers comments accurately whether you choose to display them in ascending or descending date order, on multiple pages or on one long page, and with or without threading enabled. It also handles pingback and trackback numbering.
For coders, the plugin provides additional configuration options via direct calls to the function that handles the numbering.
For more information, please see this plugin's original information page: Greg's Threaded Comment Numbering Plugin




