COLORS ON THE CARD, PARENTHETICAL EXPLAINS FLEXIBILITY (Article 86) 

Commentary:    When there are multiple colors shown in a hand, the colors indicate a change in the suit.  For example, blue does not mean Dots must be used, green does not mean Bams must be used, and red does not mean Craks must be used. You choose which suit represents each of the colors on the card. Sometimes, the league will include flexibility in the parenthesis that supersedes the colors shown for the hand (i.e., any two Dragons).   

Question from a player:  When playing a hand with three suits, do I have to follow the colors as shown on the card? 
 
Answer from the NMJL:   “A hand shown in one color represents any one-suited hand.  Two colors indicate any two suits.  Three colors represent any three suits.  A specific color on the card does not specify a particular suit.  For example, if a hand is shown in 3 colors, it means any 3 suits IN ANY ORDER.  If it is shown in green as the first color, it does not mean Bams, etc.”

Source: Mah Jongg Made Easy (2024 page 7, Suits partial)

Other answers from the NMJL:

“A specific color on the card does not specify a particular suit.  The three colors indicate that the hand must be played in any three suits.” 
 
“When a hand is shown in one color, it can be played in any suit.  When a hand is shown in two colors, it is played in any two suits.  When a hand is shown in three colors, it is of course played in the three suits.  Suits do not have to be in the order as shown on the card.” 
 
“A hand shown in one color represents any one-suited hand.  Two colors indicate any two suits.  Three colors represent any three suits.  A specific color on the card does not specify a specific suit.  For example, if a hand is shown in three colors it means any 3 suits, in any order.  If it is shown in green as the first color, it does not mean Bams.”  
 
Sources for other answers:  National Mah Jongg League Bulletin Q&A (1987 page 4, 1988 page 5, 1997 page 5, 1999 page 5, 2003, 2008, 2011, 2018, 2020 )