Chen Collection, Middle Volume. Radical: Tree (mù). Tang. Kangxi strokes: 15. Page 550, Entry 10.
According to Tang Rhymes (Tangyun), Collected Rhymes (Jiyun), and Collection of Rhymes (Yunhui), it is the same as the character for supporting. According to Explaining Graphs and Analyzing Characters (Shuowen), it refers to a pillar tilted to provide support. Xu says it is commonly written as a variant form, but this is incorrect. See the entry for the character for supporting for further details.
Additionally, according to Collected Rhymes (Jiyun), it is pronounced ding. It is read like the ding in the phrase woodcutting sound ding-ding. The meaning is the same.
Also, according to Jade Chapters (Yupian), it is pronounced tang. According to Broad Refinement (Boya), the meaning is to brace or support.