There are 5 principles that guide our use of positioning lines, slogans, tag lines and the like.

1. It must serve a purpose.
Both to the sender and receiver of the message. There must be a reason for the reader to remember it. It must serve a purpose to the viewer.

2. It should be terse and memorable with
some drama (imagination) to it.
It should create a visual image, be simple, and to the point.

3. It must be original, not like any other.
We can never confuse the viewer.

4. It must have longevity of use.
The line should have more than a one-year life to it.

5. It must be used consistently, preferably in conjunction with the logo.
Keep the visual and written elements together.

If one of these principles is violated, then it fails as a positioning line. A final thought, a general principle that we try to use in all communications art and copy is, if it works as well without "it," then leave "it" off. Artists do this all the time - delete graphic elements to keep the message clear and direct. Editors are constantly cutting copy to get the fat out. In the final analysis, if the positioning line cannot withstand this final test, then walk away from it. Walk quickly.