Add your name and the date. You should also indicate if you have applied for a patent or the registered patent number, and the same for registered designs. It is also helpful to include warnings of your rights on all documents - such as the first screen display on a computer program. You should never claim rights you do not have and there are criminal offences in the Patents Act 1977 and the Trade Marks Act 1994 where an unjustified threat of infringement is made. If you feel a big or small company is making threats for the sake of it, without any grounds, then you are entitled to a court declaration that you were not infringing their rights.
Singletons are specialist intellectual property solicitors.
If you have a legal question which you would like answered then please write to the Editor, Inventors World, clearly marking your envelope 'Inventors Legal Problems'. We regret that, due to the complex nature of Intellectual Property Law, we cannot enter into personal correspondence, nor name correspondents.