There is only one file type that uses the .NFL extension:
Nokia Flash Lite Package
File created in the Nokia Flash Lite (NFL) format, a package format used to distribute Flash Lite applications for Nokia mobile devices; saved in a compressed .ZIP format and contains a .SWF file and a text descriptor file descriptor.inf; often used for storing mobile media player skins; supported on Nokia Series 40 5th Edition, Feature Pack 1 or later devices.
NFL files may also include an 256 color icon .PNG image with a 36x36 or 43x43 pixel resolution. The icon image can include a transparent background. The icon file may only be 16Kb in size.
NOTE: Flash Lite is a technology developed by Adobe Systems. It is a lightweight version of Adobe's Flash technology.
Updated: August 26, 2011