The current version of the ANSI/ASME code uses a pipe labeling standard color code chart with six standard color combinations, and four user-defined combinations.

Some people look at a venerable resource like resistor color code charts and see something tried and true, but to [Andrew Jeddeloh], there’s room for improvement. A search for a more intuitive ...

Here’s the color code chart from the 1941 Radio Today yearbook: Ads in that magazine promoting resistors were careful to note that they were RMA color-coded.