The phrase "common lottery" refers to a type of lottery that is available and open to everyone. It suggests that anyone can participate, indicating that the lottery is not exclusive to a certain group or limited in any way. Full definition
The first year of the My School DC common lottery took place in 2014 to determine matches for new students at all participating schools for school year 2014 - 15. (myschooldc.org)
Washington Latin participates in MySchoolDC, the District - wide common lottery for K - 12 education. (latinpcs.org)
Enrollment for the upcoming school year, 2018 - 2019, is being run through the MySchoolDC common lottery process. (eagleacademypcs.org)