This chapter is from the book
This chapter is from the book
This chapter is from the book
3.3 Paragraphs
A paragraph is a sequence of sentences that traditionally represents a complete, single thought. Today, however, paragraphs are often used for structuring the text flow visually, rather than for organizing the flow of ideas within it. Online, paragraphs tend to be smaller than in print, and other means of text organization (such as blocks, 3.1.2) may make traditional paragraphs less common.
Still, whenever you have a container for more than just a small bit of text, your schema should permit inserting one or more intermediate paragraph elements between this container and its text. In most cases, this intermediate level may be optional; for example, your block elements could be allowed to contain either direct text content (for short fragments less than a paragraph) or a sequence of paragraph elements (for longer pieces of text). This approach adds a degree of laxity to your schema but is very convenient in daily markup practice.
As for the element type name, there is no reason not to use HTML's p, although para would be more appropriate for users who might find p too cryptic.
3.3.1 Lists
Lists are a special construct that is closely related to paragraphs. Two common types of lists offered by HTML are unordered (bulleted) and ordered (numbered), differing in how the items in the list are adorned. For our XML markup, we could borrow HTML's model, with a parent element (e.g., ordered-list) enveloping the entire list and children elements (e.g., item) marking up individual items.
The only possible ambiguity with regard to list markup is how to correlate list items with paragraphs. Often, each list item is a paragraph, so you may be tempted to consider paragraph elements redundant and disallow them from list markup completely. However, as soon as you run into an item of two or more paragraphs, you may regret this decision. I recommend using the convention discussed in the last section: Allow both paragraphs and direct text content within list item elements.
In fact, this is what is implemented by HTML 4; its li element can contain both inline and block content (i.e., both text children and paragraph elements, among others).
3.3.2 Paragraphs as link targets
Most links refer to entire web pages, but sometimes you need to pinpoint
a particular location within a page. In HTML, you can make a link target
from as small a piece of text as you like, down to a single sentence or
word (by enclosing it in an a element with the name
attribute).3
In most graphic browsers, however, the only visible result of jumping to
an in-page link is the page being scrolled down so that the linked point
is at the top edge of the window.
This means that - unless your linked sentence happens to start at the beginning of a screen line - the visible portion of the newly loaded page starts in mid-sentence. This result is quite confusing and makes it nearly impossible to guess what exactly the link referred to. For this reason alone, it is advisable to only allow anchoring links to block-level elements, including paragraphs.
3.3.3 Displayed material
Sometimes, you'll need to present an object that breaks the paragraph flow, but doesn't necessarily start a new paragraph. Often, this is a mathematical formula or a programming code fragment that must start on a new line.
Such a piece of displayed material is a block-level element from an HTML perspective; semantically, however, it is often an inseparable part of an adjacent paragraph containing the introductory or explanatory text for this displayed item. Therefore, it makes sense to allow the displayed material elements to be used only as children of paragraph elements.