Character Support for Arabic Ligatures
Original Publication Date: 1987-Apr-01
Included in the Prior Art Database: 2005-Feb-01
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).