Foundation HTML5 with CSS3

Constructing Content

Required Attributes

There are no required attributes for the em or strong elements.

Optional Attributes

The em and strong elements don’t have any optional attributes.

time

Introduced in HTML5, the time element represents either a precise time on a 24-hour clock or a specific

date on the calendar (with an optional time as well). The element was introduced to standardize the way

dates and times are marked up, so that browsers and web apps can potentially detect and read encoded

dates/times and, for example, allow you to add an appointment to your calendar, or alert you when there

are five minutes remaining to bid in an online auction. The possible applications for machine-readable

dates and times are limitless.

Dates in a time element must follow a specific format that scripts and user-agents can interpret: a four-

digit year, two-digit month, and two-digit day, in that order, separated by hyphens (YYYY-MM-DD). Times

in a time element must be on a 24-hour clock, not a 12-hour clock, so “2:45 pm” would be written as

“14:45”. There’s no default styling of time elements; they appear as regular text in whatever style they

inherit from their parents. Listing 4-27 shows two examples of time elements, marking a date and a time,

respectively.

Listing 4-27. Two examples of the time element

<p>We’ll be closed on <time>2012-05-05</time> but will reopen

at <time>08:00</time> sharp the following morning.</p>

The optional datetime attribute can carry the specific date and/or time in a machine-readable format,

freeing you to be more vague and human-friendly with your text:

<p>We’ll be closed on <time datetime="2012-05-05">Saturday, May 5</time>

but will reopen at <time datetime="08:00">8 am</time> the day after.</p>

A datetime attribute can include both a date and time, with the time preceded by T:

<p>We will reopen on <time datetime="2012-05-06T08:00">Sunday</time>.</p>

There are very specific requirements for formatting dates and times in a datetime

attribute, conforming to international standards. See the spec for much more detail:

w3.org/TR/html5/common-microsyntaxes.html#dates-and-times

Even with a datetime attribute, you should only use the time element for specific, known dates and times

like “August 8, 1961” or “10:02”, not for vague terms like “fifty years ago” or “an hour from now,” nor for

time spans like “77 nanoseconds” or “13.7 billion years.” Dates must also be complete—with date, month,

and year—so don’t use a time element for partial or nonspecific dates like “December 20” or “1690” or