Release Notes > 12.1.1.0 > Updates in This Release > Kerning and OpenType Shaping > Introduction
  
Introduction
Layout Developer has long had the ability to apply custom kerning values to text, but with the addition of OpenType word shaping different rules apply and, prior to 12.1.1.0, custom kerning tables were ignored when OpenType shaping was applied.
The key reason for this approach was that OpenType shaping works at the glyph level rather than at the character level. Kerning tables are specified using characters, so they no longer apply to content which has been shaped by OpenType.
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It is important to understand the relationship between characters and glyphs. In a typical font file, characters are allocated slots according their character position within the Unicode range. The ‘A’ character is always at the same code point within a Unicode font. However, OpenType allows font designers to specify different glyphs to output for any character or combination of characters; there may be several glyphs associated with the ‘A’ character, depending on which feature tables are applied. For example, the smcp table will swap the ‘A’ character for a small cap glyph. It is up to the font designer to store the glyphs where they want within the font, so there is no way to always assume that the glyph number in one font has an equivalent glyph in another font. Layout Developer provides a library tool which allows users to see the glyphs within a font.
This document provides information on the new features provided in Layout Developer 12.1.1.0 which assist the template developer to create perfect output by customising the kerning applied between both characters and glyphs.