SVG Urdu/Arabic Processing in Alphabet?

So i was looking that i am going to create whole new Unicode with my custom made glyph but the problem is that how to manage the Joining of letters i mean in Arabic there are lots of alphabet joined together and make a word unlike English in which each alphabet is separated from other so now my problem is that there is a Unicode define for a Urdu alphabet but very same alphabet join with lots of other alphabets how to handle it ? i mean there is only one unicode for that alphabet but one unicode consist lots of its shapes of join how to manage this problem of joining letters?开发者_Go百科?

and is the answer of my Problem is in This Magic Attribute ?? : arabic-form = "initial | medial | terminal | isolated"

Arabic letters change their look if they are isolated, or stand at the beginning, middle or end of a word. So a character has up to 4 presentation forms. In Unicode every one of them has it's own code and to disdinguish them the property "arabic-form" is used.

This website contains an example how to use the different glyphs from SVG:

http://www.w3.org/TR/SVGTiny12/fonts.html (see example "Font02.svg")