FORM 2 THE PATENTS ACT, 1970 (39 OF 1970) & PATENTS RULES, 2006 PROVISIONAL SPECIFICATION (SECTION 10; RULE 13) "PROCESS FOR PREPARATION OF AMORPHOUS CARVEDBLOL DIHYDROGEN PHOSPHATE" ALKEM LABORATORIES LIMITED, A COMPANY INCORPORATED UNDER THE COMPANIES ACT, 1956, HAVING ITS CORPORATE. OFFICE AT ALKEM HOUSE, DEVASHISH, ADJACENT TO MATULYA CENTRE, S.B.MARG, LOWER PAREL, MUMBAI - 400013, MAHARASHTRA, INDIA THE FOLLOWING SPECIFICATION DESCRIBES THE NATURE OF THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED FIELD OF THE INVENTION The present invention relates to a process for preparation of amorphous carvedilol dihydrogen phosphate. BACKGROUND OF THE INVENTION Carvedilol, (±)-l-(Carbazol-4-yloxy)-3-[[2-(o-methoxyphenoxy) ethyl] amino]-2-propanol, is a nonselective B-adrenergic blocker with a i-blocking activity. Carvedilol is a racemic mixture having the following structural formula (I): Carvedilol is the active ingredient in COREG®, which is indicated for the treatment of congestive heart failure and for the management of hypertension. Since carvedilol is a multiple-action drug, its beta-blocking activity affects the response to certain nerve impulses in parts of the body. As a result, beta-blockers decrease the heart's need for blood and oxygen by reducing its workload. Carvedilol is also known to be a vasodilator resulting primarily from alpha-adrenoceptor blockade. The multiple actions of carvedilol are responsible for the antihypertensive efficacy of the drug and for its effectiveness in managing congestive heart failure. Carvedilol contains an a-hydroxyl secondary amine functional group, which has a pKa of 7.8. Carvedilol exhibits predictable solubility behaviour in neutral or alkaline media, i.e. above a pH of 9.0, the solubility of carvedilol is relatively low (