I assume the parent is referring to the various control characters like "START OF HEADING", "START OF TEXT", "RECORD SEPARATOR", etc... I haven't seen most of these used for their original control purpose but they date back a long way:
They seem to be from an era when the formatting models were either fixed-width fields, or a serial set of variable width fields delineated by FIELD SEPERATOR, GROUP SEPERATOR, etc.
What both models lacked was a good way to handle optional/sparse fields. If you have a data structure with 40 sub-fields, a JSON, XML or YAML notation can encode "Just subfield 26" pretty efficiently, but the FIELD SEPERATOR model usually involves having dozens of empty fields to space the one you want, and a lot of delicacy if the field layout changes.