District of Columbia voters will cast ballots Tuesday in the city's presidential preference primary, and also decide whether to legalize certain forms of gambling, as proposed in a citizens' legislative referendum.

All registered voters will be able to vote on the gambling referendum. If approved, it would legalize bingo, raffles, social gambling such as poker where the organizer reaps no profit, a city-run daily numbers game and parimutuel wagering on dog racing and jail alai.

The rest of the items to be voted on will be determined by the party of the voter. Registered members of different parties will receive different ballots. The District of Columbia does not allow cross-over voting in the primary.

Democrats will vote for their preference for president, and also vote for possible delegates to the party's national nominating convention. The appportionment of delegates to the convention is done on the basis of the results of the presidential primary.

Fur purposes of choosing potential delegates to the Democratic National Convention, the city has been divided into two hypothetical Congressional districts. District 1 includes Wards 1,2,6 and 8. District 2 includes Wards 3,4,5 and 7. A total of 13 delegates will be chosen from the two districts.

Democrats will also nominate a candidate for delegate to Congress and choose at large and ward members for the D.C. Democratic State Committee, a national committeeman and committeewoman and their alternates.

Republican voters will vote their preference for president, nominate a candidate for delegate to Congress, choose delegates and alternates for the party's nominating convention and select members for the D.C. Republican Committee. Republican voters will also elect a national committeeman and national committeewoman and their alternates.

Members of the Statehood Party will nominate a delegate to Congress. But the party has no candidate on the ballot for either membership on its central committee or for president.

Polling places in the city's 137 precincts will be open from 7 a.m. to 8 p.m. Only those persons registered as of April 7 will be allowed to vote. Properly registered voters should bring their registration cards along with them. However, those without cards wil be allowed to cast ballots. Election day registration at the polls is not permitted in the District of Columbia.

Absentee voters may cast ballots in two ways. Those who already have ballots -- the deadline for obtaining them was Tuesday -- may mail them in, postmarked no later than May 6. Those wishing to cast absentee ballots in person may do so in Room 7 of the District Building, 14th and E Streets NW no later than 5 p.m. Friday, May 2.

Registered voters who are physically handicapped may vote in their cars and need not enter the polling place to cast ballots. Election workers will come out to assist handicapped voters if requested to do so by a friend of the voter.

Ballot punching machines will be used thoughout the city. In Ward 1, instructions on the ballot will be written in Spanish as well as English, and the wording of the initiative measure on gambling will also appear in Spanish.

City elections officials caution that for the first time, voters in all wards will receive two-sided ballots. Those voting are asked to be sure to examine and vote on both sides of the ballot before turning them in.

For more information about election procedures, residents should call the D.C. Board of Elections and Ethics, 347-9725, or the League of Women Voters, 785-2616.