Manning Nash in his 1963 paper Burmese Buddhism in Everyday Life writes:
In a village household books are a rarity. If there is a book, it is a popularized version of the essentials of the religion given here, plus one or two of the better known thok [i.e, verses], like the heart and the diamond sutras.
Nash does not provide any further information about what is meant by Heart and Diamond sutra. But I have a hard time believing that this refers to the famous Mahayana sutras.
Does anyone know which texts here are referred to as Heart and Diamond sutra?