| Hash is a namespace identifier. |
| # Root |
## Parent |
| Alpha identifies left arguments of dfns/dops. |
⍺ Left Argument |
⍺⍺ Left Operand |
| Omega identifies right arguments of dfns/dops. |
⍵ Right Argument |
⍵⍵ Right Operand |
| Del is used for self-reference in dfns/dops (as well as for the traditional APL Line Editor). |
∇ Function Self |
∇∇ Operator Self |
| Quotation marks are used to surround character strings. |
' APL Quote |
'' Empty Vector |
| Diamond character is used to separate APL statements on one line. |
⋄ Statement Separator |
| Lamp symbol is used to identify following comments. |
⍝ Comment Symbol |
| Colon is used to indicate end of line label or start of control word. It is also used in dfns and dops to separate the test from the expression in a Guard and Error Guard (two colons). |
| : End of Label |
: Start Control Word |
| Boolean: Expression |
Error Number(s):: Expression |
| Semicolon is used to separate index selection arrays in simple indexing, and to separate local names in the header of dfns/dops. |
| ; Index Separator |
; Localize Name |
| High Minus or Overbar is used to indicate that a number is negative. |
¯ Negative |