Documentation for infix (>), infix ⊃ assembled from the following pages:

Language documentation: Operators §

From Operators

(Operators) infix (>), infix ⊃ §

multi sub infix:«(>)»($a,$b --> Bool:D)

Superset of operator.

Returns True if $a is a strict superset of $b, i.e., that all the elements of $b are elements of $a but $a is a larger set than $b.

say (1,2,3) (>) (2,3,1); # OUTPUT: «False␤» 
say (1,2,3) (>) (2,3);   # OUTPUT: «True␤» 
say 4 ⊃ (1,2,3);         # OUTPUT: «False␤» 

Language documentation: Sets, bags, and mixes §

From Sets, bags, and mixes

(Sets, bags, and mixes) infix (>), infix ⊃ §

Returns True if $a is a strict superset of $b, else False. More information, Wikipedia definition.