Extension block contains additional data about Gif image. This block does not supported by 87a version.
Values
EGraphicControl(gce:GraphicControlExtension)
Graphic Control extension gives additional control over next frame, like frame delay, disposal method, alpha channel and other information.
EComment(text:String)
Commentary extension. Not show up as any visual, just a text in file.
EText(pte:PlainTextExtension)
Text extension. Must work as text rendering on the image, but ignored by all major Gif decoders.
EApplicationExtension(ext:ApplicationExtension)
Application extension allow to insert additional application data into Gif. Mostly used app extension is NETSCAPE2.0 looping extension, used to set up amount of loops in frame.
EUnknown(id:Int, data:Bytes)
Unknown extension.