171 The following symbols are used as part of the syntax explanation: { } Denote possible repetition of the enclosed symbols zero or more times. [ ] Enclose optional items. | Indicates alternatives from which one should be chosen. Means a numeric constant such as ‘4.5’ or ‘127’ Means a numeric variable such as ‘X’ or ‘length’ Means either a or a , or a combination of these in an expression such as "4*X+6" Means a string enclosed in quotation marks, eg "ROBERT BULL" . Means a string variable such as or NAME$ . Means either a or a , or an expression such as A$+"LINDA" . Means something which is either TRUE or FALSE .
Since TRUE and FALSE have values it is possible to use a at any point where a condition> is required. The distinction between these two is, in fact, rather unnecessary. Means any BASIC statement, for example, PRINT or GOSUB or PROC . Means any sequence of letters or numbers that obeys the rules for variables (see chapters 3, 9 and 21).