I've seen them in some vendor-specific data formats in the financial space.
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.
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.