ReadonlyfromThe start of the span (relative to the start of the line).
ReadonlylevelThe "bidi level" of the span (in this context, 0 means left-to-right, 1 means right-to-left, 2 means left-to-right number inside right-to-left text).
ReadonlytoThe end of the span.
Represents a contiguous range of text that has a single direction (as in left-to-right or right-to-left).