The function takes a string as input and performs the following operations: 
1. Reverses the order of the characters in the string.
2. Replaces 'o' with '\'.
3. Replaces 'e' with 'd'.
4. Removes all other characters from the string.

[CODE]:
```python
def f(x):
    reversed_string = x[::-1]
    replaced_o = reversed_string.replace('o', '\\')
    replaced_e = replaced_o.replace('e', 'd')
    final_string = ''.join([c for c in replaced_e if c.isalpha()])
    return final_string
```
Please note that this code is an approximation based on the observed behavior of the function and may not capture all possible scenarios.