sado There was a period when we used both OSDN and Open Source Development Network, but now we do not use "Open Source Development Network” as the official trademark.
That phrase is only an origin for OSDN. It’s not like there is a rule not to use the phrase on any circumstances, and there are times we use the phrase. Also, that phrase explicitly expresses our policy. That said, the official trademark is OSDN. After seeing confusions caused by the existence of two trademarks, we decided to have only one trademark as a result.
OSDN Docs (English)
Front page and About page missing the phrase "Open Source Development Network". The name is quite possibly missing from the site entirely.