The Case For a Unit Tag

11-15-11 Andy Rossi

The unit tag could be a helpful addition to the HTML5 spec.

This morning I had a short twitter conversation with Bruce Lawson regarding a possibly useful HTML5 tag: the unit tag. This tweet prompted a thought. If time could be better described through the use of an attribute, such as time type="datetime" or similar, then I think there could be room for a unit tag that could be defined by its own attribute.

Ian Hickson, while responding to the whole time tag retraction and re-addition to the spec, proposed additional tags such as geo and scalar.

One problem with scalar is that it refers to units only by their magnitude and not direction. If we want to use scalar , we would probably want a vector tag inducted down the road to even it out. Secondly, what does scalarmean to non-math types? Not a whole lot until they find out what the word “scalar” even means. If tags are to describe their contents, why use a cloudy term such as “scalar?”

Here, I feel that unit could mean more to non-math types as well as being more flexible. unit doesn’t care about dimension, so points, distance, direction, and volume could all be valid types of units. In fact, it could take the place of time in some cases. unit type="minute" makes sense, or even a more generic unit type="time" would fill that need.

The Attributes Here are a couple attribute examples that would help better define :

  • meter
  • foot
  • square-feet
  • acre
  • mile
  • torque
  • deg-farenheit
  • deg-celsius
  • hour
  • minute
  • second
  • milisecond
  • gram
  • ounce
  • pound

… and so on.

I think HTML5 could be better served with a unit tag.