What are the units of the CWC (Canopy Water Content) of the biophysical processor?


I am using the biophysical processor in SNAP 6.0. I was trying to calculate the CWC (canopy water content) but I noticed that the values were coming out to be were small. When I tried to refer to the ATBD article (http://step.esa.int/docs/extra/ATBD_S2ToolBox_L2B_V1.1.pdf) the units were changing as I kept reading the article.

On page 12, the units are grams per meter squared (g.m-2). Then on page 20, the units are now micro kilograms per meter squared. Then it changes again to grams per centimeter squared (page 41). I would appreciate if someone can clarify the units that were used in the processor.

Thank you.