| Hash identifies a namespace. |
# Root | ## Parent |
| Alpha denotes the left argument or operand of a dfn/dop. |
⍺ Left Argument | ⍺⍺ Left Operand |
| Omega denotes the right argument or operand of a dfn/dop. |
⍵ Right Argument | ⍵⍵ Right Operand |
| Del denotes the function/operator itself in a dfn/dop. (It also opens and closes the traditional APL Line Editor). |
∇ Function Self | ∇∇ Operator Self |
| Quotation marks denote character scalars and vectors. |
' Character Vector | '' Empty Vector |
| Diamond separates APL statements or array-notation segments on one line. |
⋄ Statement Separator | ⋄ Array-notation Separator |
| Lamp begins a comment. |
⍝ Comment Symbol |
| Colon in a tradfn terminates a line label or starts a control word; in a dfn/dop it forms a guard or error guard; in array notation it joins a name-value pair. |
: End a Label | : Start a Control Word |
: Guard | :: Error Guard |
: Name-value pairs |
| Semicolon separates index-selection arrays in simple indexing, and local names in the header or local lines of a tradfn. |
; Index Separator | ; Localise Name |
| High Minus indicates a number is negative. |
¯ Negative |