Special Symbols

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