Del

If you like it when your computer works, do not do this

In cartesian coordinates in three dimensions,
∇ = (i ∂/∂x + j ∂/∂y + k ∂/∂k)
where i, j, and k are the unit vectors in the x, y, and z directions respectively, and ∂/∂w is the partial derivative with respect to w.

Del operates on what is to the right of it. For instance,
∇s = i ∂s/∂x + j ∂s/∂y + k ∂s/∂k, and is called the gradient of s.

As del has components, it acts like a vector, and so the product can be taken with del and a vector. For instance the dot product of del with a vector is called the divergence
∇ • v = ∂s/∂x + ∂s/∂y + ∂s/∂k and this is a scalar quantity. The cross product of del with a vector is called the curl.

More information on del and its properties and uses is available under vector calculus. Del can also be called 'nabla.'

del is an HTML tag that is used to specify deleted text in an HTML document. While seldom used, this tag is useful for pages that need editing, but also require that the original information still be displayed. While the tag usually renders text by placing a single line through it, the tag should not be used simply for this purpose. The tag is often used in conjunction with the ins (insert) tag.

See also: ins, s, strike

Attributes

The del tag does not have any required HTML attributes. Nevertheless, it has numerous allowable attributes including:

• cite (type: URI) - a URI citing information on the reason for the change
• datetime (type: datetime) - a date or date and time specifying when the change was made
   
• HTML Core Attributes
  • class (type: CDATA) - space separated list of classes
  • id (type: ID) - document-wide unique id
  • style (type: Style Sheet) - associated style information
  • title (type: Text) - advisory title/amplification; this information is usually displayed through tooltips
     
• HTML International Attributes (I18N)
  • dir (type: Custom) - specifies the direction of weak or neutral text; valid values include ltr (left to right) or rtl (right to left)
  • lang (type: Custom) - specifies the Language Code of the language used in the deletion
     
• HTML Event Attributes
  • onclick (type: Script) - a pointer button was clicked
  • ondblclick (type: Script) - a pointer button was double clicked
  • onkeydown (type: Script) - a key was pressed down
  • onkeypress (type: Script) - a key was pressed and released
  • onkeyup (type: Script) - a key was released
  • onmousedown (type: Script) - a pointer button was pressed down
  • onmousemove (type: Script) - a pointer was moved within
  • onmouseout (type: Script) - a pointer was moved away
  • onmouseover (type: Script) - a pointer was moved onto
  • onmouseup (type: Script) - a pointer button was released

Usage

To use the del tag, simply place opening and closing HTML tags around the text is to be specified as deleted. For example (used in conjunction with the ins tag):

The next blue moon will occur on <del>November 30, 2001</del> <ins>July 31, 2004</ins>.

On browsers that support this tag, this will typically cause the date "November 30, 2001" to have a horizontal line through it. Keep in mind that the purpose of this tag is to specify deleted text, not to put a line through the text. If you simply want to put a line through your text for any other reason, you should technically use Cascading Style Sheets, however there are also the deprecated s and strike tags that will do this as well.

Everything2 Support?

E2 does provide limited support for the delete tag. It does not allow the use of any of its HTML attributes. Below is how your browser displays the example above here on Everything2:

The next blue moon will occur on November 30, 2001 July 31, 2004.

If you would like to use this tag with any of its attributes, you can do so in your Notelet Nodelet.

Common Browser Implementations*

Most web browsers support this tag, as it has been around for several years. Most browsers will display the deleted text with a single line through it, but are not required to do so.

Previous HTML Tag: dd
Next HTML Tag: dfn (next E2 supported HTML tag: dl)
See Also: HTML tags and HTML attributes

* Please feel free to send me information about how other browsers implement this tag.

Del (?), n. [See Deal, n.]

Share; portion; part.

Chaucer.

© Webster 1913.