Rational Developer for System z

Bidirectional layout (or bidirectional format) terminology

Bidirectional text can be stored on the client or server system in different text layouts (different bidirectional formats). A Bidirectional layout specifies how bidirectional text is being stored on a system. It can be defined by five basic bidirectional attributes for Arabic language, and by three attributes for Hebrew.
Global or text orientation
Global orientation designates the direction in which the text is stored. It can be right to left (RTL) or left to right (LTR). Contextual text orientation is not supported in Rational® Developer for System z®.
Ordering scheme (or text type)
The ordering scheme defines the relationship between the order of text as stored in memory or on external media and its order for proper display. Rational Developer for System z recognizes three ordering schemes:
  • In the visual ordering scheme, text is stored in exactly the same order as it is displayed.
  • In the logical ordering scheme, text is stored in the order it is intended to be read. It has to be reordered for display, using an algorithm that assumes that the letters of the Latin alphabet have a strong inherent left-to-right directionality and those of the Arabic or Hebrew alphabet have a strong right-to-left inherent directionality. This implicit (or logical) algorithm recognizes segments based on their inherent directional characteristics and performs segment inversion automatically.
  • In the smart logical ordering scheme, the text is processed with a special algorithm introduced in Rational Developer for System z to improve the data exchange between zSeries® systems and Rational Developer for System z. This algorithm in more details in Smart logical ordering scheme.
Text shaping
Text shaping is applicable to the Arabic script in which characters assume different shapes according to their position in a word how they connect to surrounding characters.
Symmetric swapping
Symmetric swapping designates when specific characters such as ( > [ { need to be interchanged with ) < ] } to preserve the logical meaning of the presented text.
Numeric shaping
Numeric shaping designates whether numbers have to be presented using the European digit shapes or the Arabic-Indic digit shapes.

No single combination of possible values of bidirectional layout attributes is predominant. Existing applications process data with different possible combinations of these values. Therefore, when a bidirectional data stream is passed to an application, it is important that the application recognize the associated text attributes.

Next: Bidirectional layout transformation (or bidirectional conversion)

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