canSpell := proc(w)
	local blocks, i, j, word, letterFound;
	blocks := Array([["B", "O"], ["X", "K"], ["D", "Q"], ["C", "P"], ["N", "A"], ["G", "T"], ["R", "E"], ["T", "G"],
                         ["Q", "D"], ["F", "S"], ["J", "W"], ["H", "U"], ["V", "I"], ["A", "N"], ["O", "B"], ["E", "R"],
                         ["F", "S"], ["L", "Y"], ["P", "C"], ["Z", "M"]]);
	word := StringTools[UpperCase](convert(w, string));
	for i to length(word) do
		letterFound := false;
		for j to numelems(blocks)/2 do
			if not letterFound and (substring(word, i) = blocks[j,1] or substring(word, i) = blocks[j,2]) then
				blocks[j,1] := undefined;
				blocks[j,2] := undefined;
				letterFound := true;
			end if;
		end do;
		if not letterFound then
			return false;
		end if;
	end do;
	return true;
end proc:

seq(printf("%a: %a\n", i, canSpell(i)), i in [a, Bark, bOok, treat, COMMON, squad, confuse]);