To estimate S&P's credit trend for EDP, S.A. from 2021 to 2022, we follow the standard corporate criteria and guidelines for Regulated Utilities.

**Step 1: Identify the relevant industry**
EDP, S.A. operates in the generation, transmission, distribution, and supply of electricity and gas. We evaluate it under the "Regulated Utilities" and standard corporate methodologies.

**Step 2: Estimate 2021 Adjusted EBITDA**
We use the reported "Profit Loss Before Provisions Amortisation And Impairment Financial Income And Financial Expenses Income Tax Expense And Extraordinary Contribution To The Energy Sector CESE" as our baseline EBITDA. 
- Reported EBITDA (2021): 3,723,050,000 EUR
- **Adjusted EBITDA 2021:** 3,723,050,000 EUR

**Step 3: Estimate 2021 FFO**
FFO is calculated by deducting cash interest and cash taxes paid from Adjusted EBITDA. 
- Cash Interest Paid (from CF statement): 481,329,000 EUR
- Cash Taxes Paid (from CF statement): 89,845,000 EUR
- **FFO 2021:** 3,723,050,000 - 481,329,000 - 89,845,000 = 3,151,876,000 EUR

**Step 4: Estimate 2021 Adjusted Debt**
We sum reported debt, lease liabilities (proxied by Right-of-Use Assets if unseparated), and pension deficits, then net out available cash. 
- Reported Borrowings (Long-term + Short-term): 15,299,588,000 + 1,518,348,000 = 16,817,936,000 EUR
- Lease Liabilities (Right-of-use assets): 1,007,029,000 EUR
- Pension Deficit (Noncurrent + Current Provisions for Employee Benefits): 940,266,000 + 179,534,000 = 1,119,800,000 EUR
- Less Cash and Cash Equivalents: -3,222,409,000 EUR
- **Adjusted Debt 2021:** 16,817,936,000 + 1,007,029,000 + 1,119,800,000 - 3,222,409,000 = 15,722,356,000 EUR

**Step 5: Calculate 2021 Adjusted Debt / Adjusted EBITDA**
- **Ratio 2021:** 15,722,356,000 / 3,723,050,000 = **4.22x**

**Step 6: Calculate 2021 FFO / Adjusted Debt**
- **Ratio 2021:** 3,151,876,000 / 15,722,356,000 = **0.200** (20.0%)

**Step 7: Estimate 2022 Adjusted EBITDA**
- Reported EBITDA (2022): 4,523,539,000 EUR
- **Adjusted EBITDA 2022:** 4,523,539,000 EUR

**Step 8: Estimate 2022 FFO**
- Cash Interest Paid: 716,454,000 EUR
- Cash Taxes Paid: 258,849,000 EUR
- **FFO 2022:** 4,523,539,000 - 716,454,000 - 258,849,000 = 3,548,236,000 EUR

**Step 9: Estimate 2022 Adjusted Debt**
- Reported Borrowings: 15,782,604,000 + 4,239,869,000 = 20,022,473,000 EUR
- Lease Liabilities: 1,320,270,000 EUR
- Pension Deficit: 644,299,000 + 126,767,000 = 771,066,000 EUR
- Less Cash and Cash Equivalents: -4,900,205,000 EUR
- **Adjusted Debt 2022:** 20,022,473,000 + 1,320,270,000 + 771,066,000 - 4,900,205,000 = 17,213,604,000 EUR

**Step 10: Calculate 2022 Adjusted Debt / Adjusted EBITDA**
- **Ratio 2022:** 17,213,604,000 / 4,523,539,000 = **3.81x**

**Step 11: Calculate 2022 FFO / Adjusted Debt**
- **Ratio 2022:** 3,548,236,000 / 17,213,604,000 = **0.206** (20.6%)

**Step 12: Classify the Year-on-Year Credit Trend**
- **Signal 1 (Leverage):** 3.81x - 4.22x = -0.41x. Because this is ≤ -0.2x, the signal is **Improving**.
- **Signal 2 (Cash-flow coverage):** 0.206 - 0.200 = +0.006 (+0.6%). Because this is between -0.03 and +0.03, the signal is **Stable**.
- **Combining the signals:** When one signal dictates a stable outcome and the other dictates an improving/deteriorating shift, the non-stable directional trend determines the overall categorization. 

<answer>Improving</answer>