A short form is often the page you sign at the counter, while the full terms sit in a longer document that is named, numbered, or sent later. The reference in the short form is what can make the longer document part of the agreement. If that reference is vague, or the longer document never reaches you, you may be holding less than the whole contract.
Find the reference
Read the short form for words such as terms, conditions, schedule, booklet, or agreement, followed by a title or a website address. Write down each one exactly as printed. If the short form says the full terms are available on request, note that too, because it places the duty to ask on you.
Check what you were given
Look for a receipt line that says you were given the full terms and how they were delivered, such as in person, by post, or by email. A signature beside a general statement is weaker evidence than a named copy. Note the issue or version mark on each page, so that you can match it to a later copy.
Ask the seller these questions
Where is the complete document, and in what form? Can I have a copy before the cancellation period ends? When does the cancellation period start, from signing or from when the full terms arrive? If the full terms never reach me, what happens to my right to cancel? Ask for each answer in writing.
Make a list of every paper
Keep a simple list with four columns: the title of each document, its version or issue mark, whether you hold a copy, and where the copy is filed. When two papers appear to conflict, look for a clause that says which one governs. If none exists, ask the administrator to say so in writing.
Where to look for the rules
Each state page on this site names the regulator and the statute that governs these sales, and it says whether the state publishes a roster. Find the page for your state, such as the Georgia page at statecoverageindex.com/georgia.html, and read the plain-words summary before you sign.
This edition has not read the contracts of any particular seller or administrator, so it cannot say what any given paper contains. Use the list above on your own papers, and take any doubt about cancellation rights to the regulator named on your state page.