X11 OpenType Bitmap (.otb)
The OTB file extension, standing for "OpenType Bitmap", is a specialized format used in X11 for bitmap-only font files. It is a variant of the SFNT (scalable font) file format, tailored to store bitmap representations of fonts without vector outlines. Historically, OTB was developed to support the efficient rendering of fonts on systems with limited resources, ensuring the high-quality display of text. This format is particularly useful in environments where rendering performance is critical, such as older display systems or embedded systems.