Note 1 — Suggestions on the Use of Colors in Mats.
Reading edition
Certain rules have been set down for combination of colors: (1) A given color with its tints and shades1 may always be safely combined; (2) complementary colors may always be safely combined; (3) the tints and shades of complementary colors may always be safely combined; (4) any three colors occurring in sequence on the color chart may be combined in that sequence.