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9. INVESTMENTS (Details 5) | 12 Months Ended
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Dec. 31, 2018
Gross Margin |
Disclosure of fair value measurement of assets [line items] |
Main assumptions (Until 2057) | Based on market studies to capture operations costs and loads, according studied of market trends.
Estimated Costs |
Disclosure of fair value measurement of assets [line items] |
Main assumptions (Until 2057) | Costs based on studies and market trends.
Growth rate in perpetuity |
Disclosure of fair value measurement of assets [line items] |
Main assumptions (Until 2057) | Growth rate was not considered due to the projection model until the end of the concession.
Discount rate |
Disclosure of fair value measurement of assets [line items] |
Main assumptions (Until 2057) | Between 5.1% to 7.9% in real terms.

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