Braille Grade class on span or div or both

## Braille Grade Indicator
In the best practices section 2.2, it currently reads:
Element(s):
span
Reserved class values:
grade-0, grade-1, grade-2
Note that terms for braille grade vary throughout the world and that grade-related class values do not directly correlate to how a local region may understand the terms. Hence, in a region where uncontracted braille is called Grade 1, grade-0 is preferred for the class name so that these terms may be better understood internationally. Basically, one should use the least value class for the least contracted grade of braille and move up in value from there.

Additionally, braille grade should only be specified when it changes within the document. Otherwise, metadata is sufficient

### The problem

The Issue is, should div also be an element on which this might occur? Let us say you have a list of spelling words. I could see the div wrapping the list and the grade class would be on this. If it is only allowed on a span, it would be constantly repeated. The span element is for inline content and the div is for block. This means you could wrap several paragraphs or other block level elements in a div.

The whole issue of what the class values should be is another question. Let us just focus on which elements for this grade change should be allowed on.