I think it is best to be very specific with them so they don't think you are trying to pull a fast one on them. If you know the details of what you want to do, spell them out. At worst, it will save exchanging letters trying to determine exactly what you mean (that may happen anyway.)
If you are trying to overturn a standing precedent, e.g., that a bipod supported mortar design predates both the Stokes design and the 1898 rule, gather as much evidence as possible and hit them with all of it at once.
If other people are doing what you want to do and it appears they have legal support for their activities, cite them as previously approved examples of what you are intending to do.