Into the breach of the bedeviling problem of matching color.
#1 - Old paint codes are unuseful. Those call out a page in a formula book. The formulas rely on pigments. The half-life of a pigment is about 10 years. They change to improve pigments, or to improve resins and the old pigment slurry is not compatible. All those old Duco/Dulux numbers are pretty useless except to maybe the 3 people in the world with the skill and supplies to match them. EMD isn't in the coach business, Boeing doesn't make engines, and paint companies aren't in the color preservation business. Here's a pantone book, pick another color. Scotland did.
#2 - Even if the paint codes are working, they marry you to a brand and type of paint. You should have the liberty to get the paint that suits your situation and standards.
#3 - The other guy can have it wrong! These are both NYC "Central Green".
Attachment:
Caboose Mismatch.jpg [ 22.12 KiB | Viewed 3119 times ]
Like Tom says over at the NYCSHS, "When I had one watch, I knew what time it was. Now I am not so sure..."
http://nycshs.org/nyc_color/index.html
The chip is Sherwin Williams from the formula from that page. I sent a chip back to NYCSHS and confirmed it was a dead ringer for the NYC/DuPont standard. And yet...
#4. Model paint is not reliable. Some model paint companies work harder than the rail museums at getting a match. But artificial light contains different color spectrums than natural light and that throws things off.
#5. Color standards? Pantone is a system based on particular pigments, see #1. I have a hunch they're preparing to deprecate a bunch of pigments and colors. Munsell is stable, since it's based on physical characteristics of light. But Munsell is fairly expensive to work with.