Browse Prior Art Database

Character Support for Arabic Ligatures

IP.com Disclosure Number: IPCOM000039003D
Original Publication Date: 1987-Apr-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Metwaly, MF: AUTHOR

Abstract

Arabic cursive script employs certain ligatures or joint characters such as lam-alef, and the letter is supported by the Automatic Shape Determination (ASD) method described in Canadian Patent 1,207,905. However, while typewriters such as the IBM Selectric Arabic typewriter support additional ligatures (Alef-Lam and Lam-Lam), the ASD has no architectural support for these. To incorporate support for products using ASD, it is merely necessary to add the new graphics to the font module, and to introduce a new, single finite state for Lam-Lam, plus two new finite states for Alef and Alef-Lam in the ASD. As originally designed, the ASD finite state machine included two states for Lam, i.e., the LM (middle-of-part shape) and LF (free-standing shape).

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Character Support for Arabic Ligatures

Arabic cursive script employs certain ligatures or joint characters such as lam-alef, and the letter is supported by the Automatic Shape Determination (ASD) method described in Canadian Patent 1,207,905. However, while typewriters such as the IBM Selectric Arabic typewriter support additional ligatures (Alef-Lam and Lam-Lam), the ASD has no architectural support for these. To incorporate support for products using ASD, it is merely necessary to add the new graphics to the font module, and to introduce a new, single finite state for Lam-Lam, plus two new finite states for Alef and Alef-Lam in the ASD. As originally designed, the ASD finite state machine included two states for Lam, i.e., the LM (middle-of-part shape) and LF (free-standing shape). By introducing a new state LL, the finite state machine is modified to operate as seen in the state diagram. The Arabic character Alef in the originally designed ASD was treated as any other character and had no dedicated state. By adding two states to ASD, state A (Alef) and state AL (Alef- Lam), the finite state machine is modified to operate as seen in the state diagram. This diagram also demonstrates the interaction of the three new states. The various reactions of the finite state machine to character selections, depending upon current state, are as follows:
1. If in LF state and LAM is keyed, the LAM-LAM ligature

is generated and the machine switches to the LL state. 2. If in L...