About the use of additional parameters #247

I found that the fluid VTK file I exported lacked some key physical quantities, such as mass, pressure, etc. What should I do if I want to output these contents in the output fluid VTK particle file? I found some information about the use of additional parameters, but I don't know what to fill in here? Can you help me? Or tell me the information grammar I should use here or where I should @chennes