"array", "box", "square"
- main use is for arrays
- also used in meta operators
- it generates "square" things (as in fuddy, old-fashioned, plain, vanilla)
Used as a brace pair or quote pair
Operators containing this character
When used inside regexes
As an Adverb
-  after an adverb can assign an Array object to an adverb but note that...
-  before an adverb is probably being used to specify a type of key for .k or .kv
- :  as an "adverb" on an identifier is used for extended identifiers when interpolation is desired.
When used as the reduce meta-operator, only certain reduce operations have identity, others require multiple elements.
Old, deprecated, or other language uses
-  is no longer a regular expression character set as in perl5. That is now <>
- [^] is no longer an inverted regex character set as in perl5. That is now <-> and <!>