This joined DP symbol has been My artist's mark since I was 14 (1970/1971).  I used it extensively in My signatures for cartoons, drawings and artwork, as well as on it's own.  When I was trying to make My way as a video game artist & animator on My Commodore C=64 and Amigas I used it as My personal & professional Trademark for identifying work that was solely Mine.  I am still using it as My artist's mark and Trademark and it can be found on My old portfolio website at Doug-Peters.com.