pdf Form M1021 - Key System Worksheet, 4-67 Popular

Identifying stations on key telephone systems (A-B-C, etc.)

Sample filled-in form used to document keyset characteristics.  Used to plan an installation, and as a reference for installers and repair techs.  Sets were identified with letters and numbers.  Letters on clear plastic number card windows (Form E-2959) are covered in BSP C37.321, I5, section 2.27.  Apparently there were "forms" from -A to -Z (except -I) with the corresponding letter on the disk (e.g. Form E-2959-A).

"At multi-station key telephone set installations, as in the 1A and 1A1 Key Telephone Systems or in 750A or 755A P.B.X. systems, etc., substitute these windows in the station number card holders for the regular windows ... to designate stations A, B, C, etc., in accordance with the work sheet data furnished with the service order.  Also refer to these letter designations when reporting station visits for either installation or maintenance reasons."

Scan is poor quality, as the original was a vintage photocopied form.  Contributed by Jeremy Walters