MNG is an image file category format. It supports all possible PNG and JPEG compression algorithms (including gamma correction and translucency) in order to create animated images. It was available in the Mozilla browser from 2000 to 2003. Now supported by Konqueror browser. MNG, i.e. Multiple-image Network Graphics, has the closest connection with PNG. In 1995, when they started developing the PNG format, it was decided not to include animation support. For a simple reason: then this feature was used infrequently. And yet, we started working on MNG, that is, the version of PNG that supports animation. The initial version of the MNG specification was born in early 2001. The MNG format is a simplified raster analogue of Adobe Flash. Each frame has many layers, and they can be moved relative to each other, scaled, cropped. This explains the complexity of supporting the MNG format. As a result, the MNG file structure resembles the PNG structure. The only difference is the identification tag. And also that much more options of blocks (chunk) are applied. MNG frames are saved as PNG or JNG. Compared to GIF, this format supports animation. Compared to JPEG, it provides the smallest file size due to compression loss. Compared to PNG, compression is done without distortion. Now MNG is not supported by popular browsers and software, since it was replaced by a simpler APNG format.
PFM is a font metric data file. It is also one of the formats of the font file category. This applies to fonts in the Adobe Type 1 (= postscript) category used by the Microsoft Windows operating system. The format contains font character sizes. He asks for the font associated file extension .PFB. It does not have the glyphs of the font itself, but with its help, the correct display of the PFB file is obtained. PFM files, that is, the Printer Font Metrics File, contain metric information about the fonts that applications use to lay out lines of text in a document. PostScipt Type 1 fonts have multiple files. The package usually comes with a couple of files with the extensions PFB and PFM. However, there may be 3 files with the extensions AFM, PFB and INF, or all 4 files - PFM, PFB, INF, AFM. Windows 7 and Windows Vista must have PFM. Modern versions of Windows have built-in tools for installing fonts of all formats. The installation procedure is the same for all font formats, but it differs for different versions of Windows. After installation, you may need to restart the application. Only then will the new fonts appear in the font list. You can open the PFM file using programs such as Adobe Photoshop, Adobe Creative Suite, Microsoft Windows Font Viewer, Microsoft Windows.