17. A computer-implemented method for constructing a text document, the method comprising: performing operations by a programmable processor of a first computer, comprising: receiving user input at the first computer selecting a character for insertion into a text document; identifying in a memory of the first computer a glyphlet representing the selected character, the glyphlet being a data structure including both a set of one or more character attributes defining semantic information of the selected character and a set of one or more glyph attributes defining appearance information for a glyph representative of the selected character, the glyph attributes including all the information necessary to render a glyph image of the glyph; inserting the character into the text document by inserting a reference to the identified glyphlet into the text document, where the reference can be used to access the sets of character and glyph attributes from the glyphlet for the character selected by the user input; and displaying the character in the text document, the displayed character being rendered from the glyph attributes.
17. A computer-implemented method for constructing a text document, the method comprising: performing operations by a programmable processor of a first computer, comprising: receiving user input at the first computer selecting a character for insertion into a text document; identifying in a memory of the first computer a glyphlet representing the selected character, the glyphlet being a data structure including both a set of one or more character attributes defining semantic information of the selected character and a set of one or more glyph attributes defining appearance information for a glyph representative of the selected character, the glyph attributes including all the information necessary to render a glyph image of the glyph; inserting the character into the text document by inserting a reference to the identified glyphlet into the text document, where the reference can be used to access the sets of character and glyph attributes from the glyphlet for the character selected by the user input; and displaying the character in the text document, the displayed character being rendered from the glyph attributes. 25. The method of claim 17 , further comprising: embedding the identified glyphlet in the text document.