A cel is an image in a specific xy-coordinate, and a specific layer/frame combination.
local sprite = cel.spriteCels belong to one sprite. This property returns that sprite.
local layer = cel.layerReturns the layer where this cel is located.
local frame = cel.frame
cel.frame = newFrameReturns the frame object which this cel belongs. If you set this property, the cel will be moved to the given frame (if another cel already exists in that frame, it will be removed).
local frameNumber = cel.frameNumber
cel.frameNumber = newFrameNumberReturns the frame number which this cel belongs, the frame number 1
is the first frame (not 0). If you set this property the cel will be
moved to the given frameNumber, check the notes of Cel.frame.
local image = cel.image
cel.image = newImageGets or sets the image with the pixels of this cel. This is the preferred way to replace the cel image, because it generates only one undoable action.
local bounds = cel.boundsReturns the rectangle with the cel bounds (position and size).
local position = cel.position
cel.position = newPositionGets or sets the cel position.
local opacity = cel.opacity
cel.opacity = newOpacityGets or sets the cel opacity. A value from 0 to 255 (which means
0=0% completely transparent, or 255=100% completely opaque).
local color = cel.color
cel.color = newColorGets or sets the user-defined color of this cel in the timeline.
local data = cel.data
cel.data = newDataGets or sets the user-defined data related to this cel (a text string).
Access user-defined and extension-defined properties of this cel.