No symbol

It is typically overlaid on a pictogram to warn that an activity is not permitted, or has accompanying text to describe what is prohibited.

For computer display and printing, the symbol is supported in Unicode by combining elements rather than with individual code points (see below).

The Ghostbusters logo is a fictional example of this, although it uses a mirror image of the symbol with the slash going from upper right down to lower left.

The regulations include the incorporation of text and pictograms, with reference to materials used, sign size, and viewing conditions.

Despite the fact that the ISO standard is freely available,[5] it is not uncommon for graphic artists to improvise on the particular color and dimensions.

Circles with red borders and no slanted or diagonal line are used under the Vienna Convention on Road Signs and Signals to indicate "No entry to vehicles with the following characteristics" (often defined on a plate beneath) such as height, width, mass, or speed.

[6] In many jurisdictions (such as Germany), 'no entry' is indicated by a solid red disc with white horizontal bar.

A blue filled circle with an illustration or legend means that a lane is restricted to a particular class of users (such as buses, cyclists, pedestrians) as shown, and no other traffic may use it.

Example: Putting W⃠ will display the letter W inside the prohibition sign: W⃠ (if the user's system handles it correctly, which is not always the case).

In the case of Webdings and Wingdings 2, the character encoding does not match the Unicode standard, so if these fonts are not present on the user's system, the symbol may not render correctly.