It belongs to TrueType and OpenType font formats and has analog compression that stores rendering technology. In WOFF it’s possible to store individual metadata with font info. It’s been used since 2010 for the main purpose of storing and transferring fonts on the Internet. It was developed by the Mozilla Foundation.
PGM is a storage format for grayscale images. Files in this format can be opened using software: ACDSee Photo Manager 14, ACD Systems Canvas 15, Corel PaintShop Pro X4. This type of file can be edited with a text editor. PGM files can be in two versions: P2 / P5. P2 are readable, P5 - to binary formats.