Mounted Image Mass

I realize that pretty much everything shapebase has mass. What I want to know is id shapeImages also have mass that is added to the object it is mounted to? For instance a player character's mass is 90 and a weapon is 15 would the combination of the two in how the player character's mass is used in physics be 105?

I ask because I see here www.garagegames.com/docs/tge/engine/structShapeBaseImageData.php there is indeed a mass variable.