What's most interesting here is the table with the date codes. It shows that the use of the vertical bars to mark the quarters started with the 'P' in 1987 since the 'Q' letter signifies 1990. This piece of ephemera both confirms the use of "QUALITY PEN" to denote the decade's worth of production. It also refutes the presumption that I made on the date code page months ago since I thought the use of the vertical bars started in 1990.
Since 1996 is the last year that can use this quarter encoding form, this implies Parker would new a new encoding form or that the 75 family line will have ended by 1996. Of course we know in retrospect that Parker ended the line in 1993.
Another inference that can be made on this document is that it came prior to 1987 since that was the first year to use this form of quarter encoding.