MEXICO CITY -- Roman Catholic leaders are planning an unprecedented open-air
 Mass next month in Mexico City's central plaza as part of a campaign to affirm
 church rights in Mexico that have been restricted for more than a century.

 The Mass will be celebrated May 6 at the entrance of the Metropolitan Cathedral
 with the crowd expected to spill across the plaza known as the Zocalo. Church
 officials found no record of a Mass or religious procession in the Zocalo over the
 past 140 years.

 The Mass is in conjunction with the National Eucharistic Congress, May 2-7,
 which is is expected to set guidelines for church policy in Mexico for the coming
 decades. The church has been restricted in Mexico since constitutional reforms
 in 1857-58 stripped it of many properties and rights. The restrictions were
 tightened with the post-revolutionary constitution of 1917. The government in 1991
 reformed the constitution to ease limits on worship.