Feature	Optimatch	HAP-E	ATLAS
AB search	Yes		No
ABDR search	Yes	Yes	Yes
AB Antigen, DRB1 allele match (for cord matching)	Yes		No
Sorting performed by Matching Engine	Yes	No	Yes
Information about probability of match at other allele at already mismatched locus	No	Yes	No?
Flexible scaling to accommodate periods of high and low use of the engine	No	Yes	Yes