How does one open and edit .dscv

[FourEightFour]

Subject kinda wraps it up, how does one edit that file type. Google seemed pretty unhelpful. What programs do you use to edit them too?

[Chacal]

Notepad? If not, try RW-Tools.
Just as a hint, most Railworks files are either:
- text files that you can directly edit with a text editor; or
- text files that have been "compiled" and need to be decompiled through serz.exe before being edited.