All the 3 way switches in this house (built in ’58) are wired as diagrammed (sorry it isn’t clearer – I couldn’t import an “easy draw” file).
The hot wire is connected to one of the “traveler wires” – the neutral is connected to the other. The “common” terminal from each 3 way is hooked to the light. In one “off” position both hot wires are connected to the light. In the other off position both neutrals.
The customer isn’t at all interested in re-wiring. This became evident when they were trying to replace old switches after painting. Thought you might find it interesting (or of course dangerous) if you haven’t seen it. It exists.
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This used to be a common way to wire 3-ways, before there was an identifed neutral, 240V systems, et al. It is no longer legal (for new work, at least) and is a hair dangerous.
You can have "interesting" problems with these when the two ends are wired to two different circuits and (in the process of upgrading the panel) the different circuits get on opposite sides of the 240V line.
A little unusual to have a house as recent as 1958 wired this way.
It might be nice to wrap a bit of tape around each end of the load's neutral just to let the next guy know that it could be hot (like with a switch leg).
If it's done in the old K&T
If it's done in the old K&T style then there's no color-coding to begin with. One side of the load is fed from one direction, the other side from the other direction -- not a cable but individual wire.