#### 4.9.11 ReadOnly

Syntax: `ReadOnly [0|1]`
Abbreviation: `RO`

sets the read only flag. When this flag is true, no editing can be performed on the document (any such attempt produces an error message). This flag is automatically set whenever you open a file that you cannot write to. See Open.

If you invoke `ReadOnly` with no arguments, it will toggle the flag. If you specify 0 or 1, the flag will be set to false or true, respectively. A lower case ‘`r`’ will appear on the status bar if the flag is true.