Internal links = links in content for Drupal 6.
Internal site links are not quite straightforward. Internal links can be generated manually using whatever or with any WYSIWYG client.
Issues crop up when using URL aliases. Counter to information on some posts on drupal, links containing references to "node/zz" or "catalog/zz" do not translate automatically to their URL aliasas. This has serious implications for usability and SEO. For SEO, or better said SEF, it is a serious problem if/when a search engine would get into the default site section that uses "node/zz" or the Ubercart standard "catalog/zz" taxonomy path: dreaded duplicates. As I understand, if duplicate on the same site, the shorter url wins. SE penalties may be in order.
Found this: - http://drupal.org/project/linktocontent D4, D5, maintenance status unknown
- http://drupal.org/project/pathfilter D5, D6, maintenance unknown, no details on D7
- http://drupal.org/project/glossify, D5, D6 maintenance unknown
- http://drupal.org/project/linodef D6 (rc), maintenance status unknown
- http://drupal.org/project/linkit D6, D7 status OK, needs pathfilter or pathologic (mentioned after enabling)
- http://drupal.org/project/pathologic D6, D7 maintenance status OK
- http://drupal.org/project/globalredirect D6, D7 maintenance status OK
- http://drupal.org/project/intlinks D7 (only), maintenance status OK
(there's more on the drupal site)
That's quite an array of options. Now need to focus on what's maintained and, possibly, "forward looking" from the D6 to D7 point of view.
After some experimentation and research, the following appear to be a good solution:
- http://drupal.org/project/globalredirect D6, D7 maintenance status OK, plus - http://drupal.org/project/pathologic D6, D7 maintenance status OK
1. Global Redirect ensures that all paths follow the URL aliases, regardless of what the link is defined for.
2. Pathologic allows the use of generic (node/zz, catalog/zz, etc) link definitions in content, then filters the viewable output (what users and search engines see at the bottom link address bar) to be in the form of the URL alias - instead of a visible node/zz reference - when pathologic is not used. This has the advantage that when any URL alias is changed, the visible links change with it.
Looks like an "elegant" solution. Both modules are easy to install and set up.
Purely concerning the topic of "internal links" the module - http://drupal.org/project/intlinks D7 (only), maintenance status OK might be effective, but I have not tested it, because I do not need it.
In end-effect this topic has strayed deviated from "internal links" to effective and stable URL aliases, including (manual) internal links. My apologies for the topic deviation.
Global Redirect is a terrific module. It also works very well together with the Pathologic module.