Optical margin alignment outdents characters with partial or slanting sides, such as A, V, W, Y, and punctuation, into the margins so as to make the text border appear vertical to the human eye. Optical margin alignment of punctuation marks is known as hanging punctuation.
Use
It is designed to be used for body text, not for artistic text, table text, or headlines. It also works well for block quotes, which benefit from so-called hanging punctuation. “Smart quotes” are outdented 100% into the margin or paragraph indent, so that subsequent lines of text align with the first character in the quotation.
The optimal values used for the outdents is font dependent. A typeface that has capital A, V, W, and Y with vertical sides, needs no outdents for these letters, but the capital T and punctuation will still benefit from using Optical Margin Alignment.
If text has narrow gutters between columns, table borders, or any straight edge such as an image near to the edge of the text, Optical Margin Alignment should not be used because the proximity of the straight line will break the optical illusion.
This technique is sometimes called hanging punctuation, as it is useful mostly for punctuation marks such as comma, period and the like. However, margin kerning, the slight shifting of certain characters at the margins so the margins look smooth, is a more general concept, as it can be usefully applied to certain letters as well.
Suggested Values for Optical Justification
These values may be suitable for common seriffed fonts like Times New Roman, Palatino, or Garamond. Other fonts may need different values.
| Characters | Value |
|---|---|
| " “ ” ' ‘ ’ , . | 100% |
| hyphen | 75% |
| en-dash | 50% |
| em-dash | 25% |
| A T V W Y | 20% |
| C O | 10% |
External links
- Micro-typographic Extensions of pdfTEX in Practice - Hàn Thé Thành, University of Education, Ho Chi Minh City, Vietnam