Bitmap fonts are simply collections of raster images of glyphs. These fonts are rarely designed by typographers familiar with APL glyphs. Few fonts are known to support these glyphs. Linotype fonts that support Romanian glyphs mostly follow this convention. Contextual kerning refers to positional adjustment that depends on more than two consecutive glyphs. Arial Unicode MS also includes Hebrew glyphs different from the Hebrew glyphs found in Arial. Font designers may want to optimize the display of these composed glyphs. The blackletter style is then determined by a font with blackletter glyphs. It includes Cyrillic and polytonic Greek glyphs for classical studies use. Caslon Ornaments is a typeface containing ornament glyphs. Also, a font with many types of glyphs may require several such tables. Katakana glyphs in the same row or column do not share common graphic characteristics. All three types may be augmented with syllabic glyphs. Vowels themselves have their own glyphs. Type glyphs (characters) are created and modified using illustration techniques.