| 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 | |
The following National Language characters may be used in names:
À Ä Å Æ É Ñ Ö Ø Ü ß à á â ä å æ ç è é ê ë í î ï ñ ó ô ö ø ù ú û ü
The three special characters
_ ∆ ⍙
can also be used in names.