On April 25th, the SEC provided notice of the Chicago Board Options Exchange's proposal to adopt three forms of Self-Trade Prevention modifiers: The Cancel Newest, Cancel Oldest, and Cancel Both Self-Trade Prevention modifiers. A CBSX Trader may elect for all of his proprietary orders and quotes to be marked with a Self-Trade Prevention modifier. If a CBSX Trader makes such an election, any quote or order he submits will be prevented from executing against a resting opposite side order or quote that is labeled as originating from the same associated acronym and trading for the same account (for the purposes of this Rule, the "Same CBSX Trader"). A CBSX Trader may only elect for one of the three Self-Trade Prevention options, as the CBSX System may only be configured to permit one such election. Such election shall apply to all of the CBSX Trader's eligible proprietary orders and quotes. As such, Self-Trade Prevention elections cannot be made on a per-order, per-quote, or security-by-security basis due to CBSX System limitations. Any of the Cancel Newest, Cancel Oldest, or Cancel Both Self-Trade Prevention modifiers may be accommodated on the CBSX System. Comments should be submitted within 21 days after publication in the Federal Register, which is expected during the week of April 30. SEC Release No. 34-66860.