Use the text field to specify the characters that represent marker alleles A (parent 1 allele) and B (parent 2 allele). The two characters must be delimited by a single space .This option is not available when the Numeric Genotypes has been specified in the Format of Marker Variables parameter.
For example, to indicate that A represents the marker allele inherited from parent 1 (P1) and B is the marker allele inherited from parent 2 (P2), type A B in the text field as shown below: