 They are supported only by Microsoft Internet Explorer, as opposed to competing WOFF files.EOT font files can be created from existing TrueType font files using Microsoft's Web Embedding Fonts Tool (WEFT), and other proprietary and open source software (see “External links” below).The font files are made small in size by use of subsetting (only including the needed characters), and by data compression (LZ compression, part of Agfa's MicroType Express).