system: You are a contract-analysis assistant performing a span-extraction task. You are given an excerpt from a commercial contract and the name of a clause type to locate within it.

Return the exact text of the requested clause, copied verbatim from the excerpt — identical wording and punctuation, with no paraphrasing, summarising, explanation, or added commentary.

The excerpt is one window of a much longer contract and often will not contain the requested clause. If the requested clause does not appear in this excerpt, respond with exactly: Not found.

Output only the extracted clause text, or the exact string `Not found.` — nothing else.

user: Contract excerpt:
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GENF module, which produces the sum or product of two independently generated sine waves as its output. Each sine wave can be individually parameterized. A.4.l Functional requirements: The GENF module is designed to generate a wide range of DTMF, Call Progress Signals, MF Rl/R2, and miscellaneous tones. In order to meet or exceed international telecommunication specifications, GENF must meet or exceed the following functional requirements. 1. Independent arguments shall be supplied for each frequency for dual tones that GENF generates. Single tones are generated by specifying that one of the dual tone's frequencies is 0 Hz. 2. Independent arguments shall be supplied for the carrier and modulation frequencies for amplitude modulated tones that GENF generates. 3. Arguments shall be supplied that allow the frequency of a tone to be set in the range of 0 to 4000 Hz in 1 Hz units. 4. Arguments shall be supplied that allow the output power to be set in the range of +3 to -50 dBm in 0.5 dB steps. 5. Arguments shall be supplied that allow an amplitude modulated tone's modulation percentage to be set in the range of 0 to 300% in 1% units. 6. The tone duration (make time) shall be specified in 1 ms units. Tone durations shall be specified in the range of 0 to 8191 ms. Software License D2 Technologies, Inc. and Maintenance Agreement August 4, 1997 CONFIDENTIAL 26 7. An unlimited tone duration shall be specified by setting the make duration to -1. 8. The silence duration between tones (break time) shall be specified in 1 ms units. Silence durations shall be specified in the range of 0 to 8191 ms. 9. An unlimited silence duration shall be specified by setting the make duration to -1 and setting both frequencies of a dual tone to 0 Hz. 10. The GENF module shall allow tones to be generated that meet or exceed EIA/TIA-464 requirement for DTMF and call progress tone generation. 11. The GENF module shall allow tones to be generated that meet or exceed CCITT Blue Book Volume VI Fascicle VI.4 recommendations Q.310-Q.490 requirements for MF R1 and R2 tone generation. 12. The GENF module shall generate tones with one to three unique cadence pairs (on/off pairs). A.4.2 Performance Requirements 1. Frequency accuracy shall exceed 1 Hz. 2. Level accuracy shall exceed 0.5 dB. 3. Timing information shall exceed 1 ms accuracy. A.5 Universal Tone Detector A.5.l Overview The Universal Tone Detector (UTD) is a high configurable tone detector. By changing parameters, this algorithm can classify a wide range of single and dual tone call progress signals generated in a wide variety of countries. A.5.2 General Since different tones need different detection heuristics, and tones may have multiple specifications, each tone is tagged with a tone category identifier. Software License D2 Technologies, Inc. and Maintenance Agreement August 4, 1997 CONFIDENTIAL 27 ----------------------------------------------- Tone Category Call Progress Signal ----------------------------------------------- 1 Modem 2 FAX CNG 3 Audible Ringback 4 Busy 5 Reorder or Congestion 6 Number Unobtainable 7 SIT 8 Dial tone 9 Unknown Tone ----------------------------------------------- Table A-3: Tone Categories In addition to specifying a tone category, the parameters include a value that is returned to the application when the tone is detected. This parameter need not be unique. This allows multiple specifications to report the same tone event to the application. UTD is table driven. Using this approach, the tone detector searches parameter tables for a matching tone. When a tone matches, the tone code determines the heuristics necessary to completely classify the tone. Also, the tones must be specified in a way that a set of parameters corresponds to either a single tone, a dual tone, or an amplitude modulated tone. --------------------------------- Code Tone Type --------------------------------- 0 Single Tone 1 Dual Tone 2 Modulated Tone --------------------------------- Table A-4: Call Progress Tone Types A.5.3 General Functional Requirements UTD functionally combines a single tone detector and a dual/modulated tone detector into a single module. UTD combines the results of these detectors into a single result. UTD has the following requirements. 1. The DSP shall indicate that the first ringback has started after at least 400 ms of ringback like signal has been processed, as long as no other tone type is early detected. If more than one type of tone is early detected, the first ringback reporting shall be delayed until either cadence information disqualifies the other types, or tone precedence is used as a 'tie-breaker'. Software License D2 Technologies, Inc. and Maintenance Agreement August 4, 1997 CONFIDENTIAL
"""

Extract the exact clause related to "Post-Termination Services" from the excerpt above.

assistant: Not found.