A will asks the living to interpret instructions whose author can no longer clarify a single word.

Instructions outlive the only person who could explain them. The words were written by someone who assumed they were clear, and now the living have to interpret them without any way to ask a single question, which is why these documents cause so much difficulty. Clarity is only ever tested by absence.

So write down more than the instructions when you can, including why. And if you are on the receiving end of an unclear intention, try to work out what the person cared about rather than parsing the wording. Where several readings are possible, choosing the most generous one towards the people involved is usually closest to what they would have wanted.