Because of several dropped lines, a report on changes in Senate rules in yesterday's editions incorrectly stated that conservatives had used delaying tactics to tie up the Senate on natural gas legislation during the past Congress. The paragraph should have said that conservatives had used the tactics on labor law revision while liberals had delayed action on natural gas deregulation.

The Senate yesterday voted a major strengthening of its anti-filibuster rule as it prohibited the recently discovered post-cloture filibuster. The vote was 78 to 16.

Twenty years ago, when southerners were filibustering civil rights bills, it was generally understood that a Senate vote to limit debate was the effective end of the filibuster. Each senator could still talk for one hour but when time ran out the Senate voted on the issue before it.

Recently Senate rules experts such as the late James B. Allen (D-Ala.) found a way to keep the filibuster going after cloture. Any amendment filed before cloture was voted could be brought to a vote after it. Hundreds of amendments could delay the Senate for weeks.

Conservatives used it to tie up the Senate for two weeks as they called up dozens of amendments in a vain attempt to stop deregulation of natural gas prices.

Senate Majority Leader Robert C. Byrd (D-W.Va.) threatened last year to try to push through rules changes at the start of this Congress to permit the Senate to bring issues to a vote. He offered a package of changes on the first day of the 96th Congress Jan. 15 and the Senate has done nothing except talk about them occasionally since.

Byrd proposed that every senator still have one hour to talk after cloture, but that the 100 hours cover everything, including roll-call votes on amendments and quorum calls. By three-fifths vote the Senate could extend this period.

Byrd had proposed that the 100 hours could be squeezed down to 30 by three-fifths vote. After he agreed to give that up yesterday morning, Republicans agreed to bring the rules change to a vote late yesterday.

In exchange Byrd is now expected to drop his attempt, which Republicans strongly oppose, to bar a preliminary filibuster on a motion to take up a bill. Opponents now get two cracks at a delaying filibuster, once on a motion to take up the bill and then on the bill itself.

This is only the third time the Senate has acted to make it easier to break filibuster. Until 1917 there was no rule, no way to make the Senate vote as long as anyone wanted to talk.