What is "corvision"

CorVision is a fourth generation programming tool ( 4GL) currently owned by Attunity, Inc. CorVision was developed by Cortex Corporation for the VAX/VMS ISAM environment. Although Cortex beta tested CorVision-10 which was generated for PCs but CorVision itself stayed anchored on VMS. CorVision-10 proved more difficult than hoped, and was never released.