If an application claims more than one invention, the examiner should require the applicant to elect only one for examination.

Example: Suppose inventor Ogg invented the wheel, and went on to invent the spoked wheel and the rubber tire. The claims in his application might be:

  1. A wheel having spokes.
  2. A wheel having a rubber tire.
The examiner would require Ogg to elect between inventions 1 and 2. Only claims for the elected invention can be allowed. A divisional application may be filed for the non-elected invention.

Now suppose there were a broad "umbrella" claim covering all the species:

  1. A wheel.
  2. A wheel having spokes.
  3. A wheel having a rubber tire.
Here claims 2 and 3 are species of the invention of claim 1. Because claim 1 may not be patentable, the examiner will require Ogg provisionally to elect one of the species for examination. The result is the same, except that if claim 1 is found to be patentable, all three claims can be allowed.