DigiKey might want to change the parametric search listing for the transformer listed in the subject line (DigiKey P/N 237-1965-ND). The F-313X datasheet shows a schematic with a center tap, and calls out a green/yellow wire for it, but the photo and mechanical drawing on the datasheet show no such wire, and no such wire is present on the actual item.
(Making it worthless for my current project, but I’ll probably find a use for it somewhere else.)