Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See Parameter IDs.
Parameter: Enable
VP_WATERMARK_TEXT_ENABLE
Parameter: Dynamic Layout
VP_WATERMARK_TEXT_DYNAMICLAYOUT
Parameter: Show Labels
VP_WATERMARK_TEXT_SHOWLABELS
Parameter: Time Code
VP_WATERMARK_TEXT_TIMECODE
Parameter: Render Time
VP_WATERMARK_TEXT_RENDERTIME
Parameter: Active Camera
VP_WATERMARK_TEXT_ACTIVECAMERA
Parameter: Date
VP_WATERMARK_TEXT_DATE
Parameter: Project Name
VP_WATERMARK_TEXT_SCENENAME
Parameter: Polygon Count
VP_WATERMARK_TEXT_POLYCOUNT
Parameter: Version Info
VP_WATERMARK_TEXT_C4DVERSION
Parameter: Machine Info
VP_WATERMARK_TEXT_MACHINEINFO
Parameter: Take
VP_WATERMARK_TEXT_TAKE
Parameter: Footer
VP_WATERMARK_TEXT_CUSTOM
Parameter: Text
VP_WATERMARK_TEXT_CUSTOM_TEXT
Parameter: Background Opacity
VP_WATERMARK_TEXT_BG_OPACITY
Parameter: Vertical Alignment
VP_WATERMARK_TEXT_POS_Y
Parameter: Font
VP_WATERMARK_TEXT_FONT
Parameter: Color
VP_WATERMARK_TEXT_COLOR
Parameter: Background Color
VP_WATERMARK_TEXT_BG_COLOR
Parameter: Enable
VP_WATERMARK_IMG_ENABLE
Parameter: Filename
VP_WATERMARK_IMG_FILENAME
Parameter: Opacity
VP_WATERMARK_IMG_OPACITY
Parameter: Blend Mode
VP_WATERMARK_IMG_BLENDMODE
Parameter: Horizontal Alignment
VP_WATERMARK_IMG_POS_X
Parameter: Vertical Alignment
VP_WATERMARK_IMG_POS_Y
Parameter: Margin
VP_WATERMARK_IMG_MARGIN
Parameter: Scale
VP_WATERMARK_IMG_SCALE
Parameter: Keep Aspect Ratio
VP_WATERMARK_IMG_SCALE_ASPECT
Parameter: Keep Original Size
VP_WATERMARK_IMG_SCALE_KEEPSIZE
Parameter: Add Multipass Layer
VP_WATERMARK_ADVANCED_ADDMULTIPASS
Parameter: Render HUD
VP_WATERMARK_ADVANCED_RENDERHUD