Can anybody explain what's the point of this and in what kind of situations a pilot needs it?

**ICAO Doc 9432 "Manual of Radiotelephony"**

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> 8.3.3 An aircraft may request a clearance to climb or descend maintaining own separation while in VMC, in daylight, below 10 000 feet in airspace classes D and E. The clearance shall include information on essential traffic.
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> *Example:*
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> P: FASTAIR 345, REQUEST VMC DESCENT TO FL 60  
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> C: FASTAIR 345, DESCEND TO FL 60, MAINTAIN OWN SEPARATION AND VMC FROM FL 90 TO FL 70, TRAFFIC WESTBOUND FRIENDSHIP FL 80, ESTIMATING WICKEN VOR AT 07.
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