If I want to update a document file on Windows Operating System, but that file is "Read-Only", so I can't update the document file.
In this case, I want to use "write" to express the meaning, I would say:
A. Write is proteced.
B. Write protected.
Which is correct? A or B ? and why?
...It just is. When Windows wants to assign permissions for various different forms of access to a file, it names each form of access after the action permitted - Read, Write, Execute ... not sure if there are any others. It's a new word, and it refers to something quite distant from the real world. You think you're writing, but as far as the computer is concerned you're just organizing 1s and 0s. Among programmers and systems engineers, write can be a noun: 'The program is doing a write.' This noun can be prefixed to 'protected' to specify a sort of protection.
If Windows won't let you re-organize the 1s and 0s that are arranged in a way that appears to you as a readable file, it calls that file 'Write-protected'.