Letters patent appeal override CPC etc?

NOW THE LATTER  OF PATENT APPEALS ARE NOT FILLED IN H.C OF A.P,  IT IS OVERIDED BY CPC.

Thank you Sir.

Letter patent is the charter under which the High COurt is established. The powers given to a high Court are akin to the constitutional powers of a high court.  Letters Patent is treated as law and its application is limited only to the Charted High Court. It prescribes powers and procedure on the original side of high court and in that aspect it take precedence over civil procedure code.

Even now, we follow letter patent procedure in Madras High Court we file appeal against civil side order/judgement and it is called LPA (letter patent appeal).

Can anyone give full details of Letter Patent? What is it? How and where such application be made?