Many google experts say that google doesn't understand underscores in URL. The search engine doesn't care of underscore and considers dash separated words as an unique word, which is not good for ranking.

ie: the page http://ez.no/community/articles/open_funding_the_defeat_of_dysfunctional_development is indexed in 3 keywords: "community", "articles", and "openfundingthedefeatofdysfunctionaldevelopment"

Many experts advice to use dash in URL to improve google ranking.

The url in the first example should be http://ez.no/community/articles/open-funding-the-defeat-of-dysfunctional-development which allows google to index the page on each word ("community","articles","open","funding","defeat","dysfunctional","development")

here is a patch which alter lib/ez18n/classes/ezcodemapper.php to force eZ to publish content with dashed URL.

I test on 3.9.1 and it works (just take care to patch eZ before anything).

It could be usefull to promote this enhancement for a future release.