Use this field to specify additional variables across the meta-analysis that contain SNP identifiers.This field is used only when one or more of the data sets selected, after the first, uses a variable with another name for the SNP ID Variable. All variable names for the 2nd through the last data set must be specified here.
For example, to specify the additional SNP variables Marker_1 and Marker_2, type Marker_1 Marker_2 in the text box, as shown below: