tokens: ['As', 'described', 'in', 'TS', '', '', 'the', 'CTF', 'an', 'integrated', 'component', 'in', 'each', 'charging', 'relevant', 'NE', 'generates', 'charging', 'events', 'and', 'forwards', 'them', 'to', 'the', 'CDF', 'The', 'CDF', 'in', 'turn', 'generates', 'CDRs', 'which', 'are', 'then', 'transferred', 'to', 'the', 'CGF', 'Finally', 'the', 'CGF', 'creates', 'CDR', 'files', 'and', 'forwards', 'them', 'to', 'the', 'BD', 'If', 'the', 'PCN', 'generating', 'the', 'charging', 'information', 'has', 'an', 'integrated', 'CDF', 'then', 'the', 'PCN', 'can', 'produce', 'CDRs', 'The', 'CGF', 'may', 'also', 'be', 'integrated', 'in', 'the', 'PCN', 'or', 'it', 'may', 'exist', 'as', 'a', 'physically', 'separate', 'entity', 'If', 'the', 'CGF', 'is', 'external', 'to', 'the', 'PCN', 'then', 'the', 'CDF', 'forwards', 'the', 'CDRs', 'to', 'the', 'CGF', 'across', 'the', 'Ga', 'interface', 'In', 'this', 'case', 'the', 'relationship', 'between', 'PCNCDF', 'and', 'CGF', 'is', 'm', 'If', 'the', 'CGF', 'is', 'integrated', 'in', 'the', 'PCN', 'then', 'there', 'is', 'only', 'an', 'internal', 'interface', 'between', 'the', 'CDF', 'and', 'the', 'CGF', 'In', 'this', 'case', 'the', 'relationship', 'between', 'PCNCDF', 'and', 'CGF', 'is', '', 'An', 'integrated', 'CGF', 'may', 'support', 'the', 'Ga', 'interface', 'from', 'other', 'PCNCDFs', 'If', 'the', 'CDF', 'is', 'external', 'to', 'the', 'PCN', 'the', 'charging', 'events', 'are', 'transferred', 'from', 'the', 'PCN', 'to', 'the', 'CDF', 'via', 'the', 'Rf', 'interface']