Wikipedia has blocked editing rights from some computers at the US House of Representatives in response to "disruptive" revisions of the online encyclopedia.
A 10-day ban imposed Thursday blocked any editing from an IP address at the US Capitol, which is shared among a number of computers.
"You have been blocked from editing for a period of 10 days for persistent disruptive editing," a Wikipedia posting said.
The move came after unusual revisions were pointed out by Twitter account @congressedits, which describes itself as "a bot that tweets anonymous Wikipedia edits that are made from IP addresses in the US Congress."
The account was created by a software developer named Ed Summers.
Some of the changes, which were later undone, said that John F. Kennedy's assassin Lee Harvey Oswald acted "on behalf of Fidel Castro" and that the news blog Mediaite was "sexist" and "transphobic."
While Wikipedia allows users to contribute and edit entries, it also monitors for unverified or unsubstantiated comments.
A notice posted on one of the anonymous entries from Congress said: "Please refrain from making unconstructive edits to Wikipedia... Your edits appear to constitute vandalism and have been reverted or removed.
"Administrators have the ability to block users from editing if they repeatedly engage in vandalism."
A spokeswoman at the Wikimedia Foundation, which operates Wikipedia, pointed out that the block only applies to a single IP address, not all computers located in Congress.
"The Wikipedia community is the arbiter of administrative decisions related to community editorial policies," spokeswoman Katherin Maher said in an email.
"In this case, the decision was made by a member of the English Wikipedia community, based on their assessment that the IP address in question was being used for disruptive editing. Wikipedia English has a behavioral guideline against disruptive editing."
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