Alignment and justification

rendition alignment
keyword

Use of the align keyword to encode horizontal alignment of elements whose position on the page is vertically constrained

Alignment has to do with the horizontal location or longitude of an entire element or text chunk within the overall text block. It makes most sense to think of representing the alignment of elements whose horizontal position can vary from side to side (for instance, stage directions or headings) but whose vertical position is fixed by where they are encoded in the stream of text. The align keyword is different in this respect from the place keyword, which indicates both vertical and horizontal position for elements that can appear anywhere on the page, and whose position is not indicated by where they appear in the stream of encoded text (for instance, notes or handwritten additions).

Alignment should also be distinguished from justification, which describes whether a given text block has a strict vertical edge on the left or right side (or both). Text chunks that are aligned to a certain side of the page are often also justified on that same side, since the visual effect of alignment is strengthened by the visual line of the justified margin, but this is not always the case (for instance, closing salutations in letters are often aligned to a point close to the center of the page, but are justified on the right).

Alignment and justification are arguably less essential aspects of the source document’s rendition than facets such as font and case, since they have so much to do with the dimensions of the original page (and hence don’t translate effectively to a flexible digital display). Of the two, justification is the less useful and we do not recommend capturing it unless you have a clear rationale for its use. We recommend capturing alignment only in general terms.

The align keyword may have the values right, left, center, inside, and outside. The inside and outside values are useful for textual features such as page numbers which are always aligned symmetrically with respect to the book’s opening, rather than having a consistent position on each page.