Spelled vs. spelt
In American English, spelt primarily refers to the hardy wheat grown mostly in Europe, and the verb spell makes spelled in the past tense and as a past participle. In all other main varieties of English, spelt and spelled both work as the past tense and past participle of spell, at least where spell means to form words letter by letter or (with out) to make clear. Outside the U.S., the two forms are interchangeable in these uses, and both are common.