I have here an authentic IBM flowcharting template Part No. GX20-8020-2. I node this information for posterity so that future generations may be able to decypher those arcane symbols stored in our massive 20th century archives...

The symbols on this envelope and the enclosed template conform to the International Organization for Standardization (ISO) International Standard 1028 - "Information Processing-Flowchart Symbols", and American National Standard, Flowchart Symbols and Their Usage in Information Processing, ANSI X3.5-1970. IBM usages beyond the above standards are these three symbols: off-page connector, transmittal tape, and keying, which are identified IBM.

Measurement: Top edge has two 4 inches rulers, one measured in eights another in tenths of inches. Left side has a 9cm metric ruler. The bottom has two rulers of twelveths and fifteenth of inches.
The right edge of the plastic template includes a stencil to facilitate drawing the { and } symbols.