System 21 is an Enterprise Resource Planning solutions. It was originally released by the firm JBA [1], then went to Geac Computer Corporation with Geac's acquisition of JBA. In 2007 Geac was acquired by Golden Gate Capital for $1 billion at which time, control of System 21 software fell to Infor Global Solutions, a Golden Gate subsidiary.
System 21 is a solution that operates on IBM's System i (a.k.a. AS/400) hardware platform. It is actively developed by Infor, and is participates in Infor's Open Service Oriented Architecture (SOA)
A 'Redbook' guide to implementing System 21 is available from IBM Corporation here.
References
System 21 Wikipedia(Text) CC BY-SA