An NSArray of NSNumbers.

This provides a means to override the default bidi algorithm, equivalent to the use of bidi control characters LRE, RLE, LRO, or RLO paired with PDF, as a higher-level attribute. This is the NSAttributedString equivalent of HTML's dir attribute and/or BDO element. The array represents nested embeddings or overrides, in order from outermost to innermost. The values of the NSNumbers should be 0, 1, 2, or 3, for LRE, RLE, LRO, or RLO respectively; these should be regarded as NSWritingDirectionLeftToRight or NSWritingDirectionRightToLeft plus NSTextWritingDirectionEmbedding or NSTextWritingDirectionOverride.

Available in Mac OS X v10.6 and later.