1. A method for calculating a position of a current line of glyphs relative to an immediately preceding line of glyphs, the method comprising: receiving a document containing lines of glyphs, each line of glyphs including at least one glyph, each glyph being contained in an embox having a preceding edge and a following edge, the embox having a size determined by a type size of a character represented by the glyph, wherein a line of glyphs includes a preceding line defined to coincide and be parallel with the preceding edge of a largest embox of the line of glyphs, a following line defined to coincide and be parallel with the following edge of the largest embox of the line of glyphs, and a line height defined to be a distance between the preceding line and the following line of the line of glyphs; receiving an input specifying a line leading metric, which represents a reference point relative to an embox; receiving a line leading value for the current line of glyphs and a line leading value for the immediately preceding lines of glyphs; calculating the line height of the immediately preceding line of glyphs; calculating a position of a line leading measure point of the immediately preceding line of glyphs from the line leading metric and from the line height of the immediately preceding line of glyphs; calculating a position of a line leading measure point of the current line of glyphs from one of the line leading values received and from the calculated position of the line leading measure point of the immediately preceding line of glyphs; calculating the line height of the current line of glyphs; and calculating the position of the current line of glyphs from the line leading metric, the line height of the current line of glyphs, and the calculated position of the line leading measure point of the current line of glyphs.