I think it tends to be regional and typically it's a pre-mixed color as opposed to a custom color. When I lived in CA, many builders used Navajo White, Linen White, and Antique White. Here's a quote about Navajo White from Wikipedia, "From the 1970s to the 1990s it was the standard interior paint color used in most tract homes in the United States and especially apartment complexes as it does not show stains from cigarette smoke or fingerprints."

Some paint manufacturers have stopped making these pre-mixed whites opting for a single bright white and mixed colors. Some of these colors might be browner some more yellow. Here's some colors use as a starting point in your search.

Benjamin Moore's Navajo White 947, Linen White 912, Antique White OC-83

Sherwin Williams Navajo White SW6126, Crisp Linen SW6378, Antique White SW6119

Kelly Moore Paints Navajo White 36, New Linen 29, Antique White 49

Dunn Edwards Navajo White DEC772, Cottage White DEW318

Behr (Home Depot) Navajo White 1822, Linen White 1070, Cottage White 1813

There's probably a few more, but I've got to get the kiddos to bed.

I hope you find it!

Kathe