Tim Gilbert wrote:

Feeling brilliant after those endeavours, I decided to tackle the New
York Central armed with the ORER's and NYC's Freight Car Diagrams.
Here, I was bombarded with changing Lot Numbers, rebuilds,
renumberings, changing Mechanical Designations, etc.. It seemed that
from the footnotes from the ORER's that the NYC assigned some freight
car number series to the auto plants rather than car types. I gave up
- Jeff English who forgotten more about the NYC than I will ever know
said I was foolish to even try such a task.

I dabbled with the same idea and also went to Jeff to confirm my suspicion
that the problem is a many to many relationship -- one Car Lot, on an
As-Built basis, might be found in multiple car series in the ORER. On some
later date one or more of those car series get combined with like cars from
a different Car Lot and renumbered so now one lot has many car series and
one car series has many lots.

There is a simple technical solution (non-excel based) to that but I
concluded it requires far more effort to set up and capture the answer than
the end result was worth. Now perhaps w/ a dozen or more ORER sets, it
would be, but in the 1-3 range it, IMO, isn't.

Dave Nelson