This non-standard, browser-specific property is not recommended. Authors should generally find an alternative way to accomplish the same task while adhering to all best practices, or simply do without it if it is unimportant.
user-modify property, described by the W3C in 2000 and superseded (but apparently not replaced) in 2004, determines whether a user can edit the content of an element. It is implemented in Safari as
-webkit-user-modify and in Mozilla as
|The content is read-only.|
|The content can be read and written.|
|The content can be read and written, but any rich formatting of pasted text is lost.|