Since you mention COBOL records were variable-length I'd guess that they probably contained ODOs (Occurs-Depending-On, variable length arrays for those of you w

Since you mention COBOL records were variable-length I'd guess that they probably contained ODOs (Occurs-Depending-On, variable length arrays for those of you who aren't COBOL literate). In order for a group or record MOVE to work properly you had to move the subordinate ODO values first, otherwise the runtime system would miscalculate the target record length, possibly truncating the MOVE. This also meant you couldn't use READ INTO for variable length records (which is equivalent to a READ followed by a MOVE) without taking some care. As you say: "newbies shake their heads..."