Literal Strings:

A literal string is a sequence including any characters and delimited by the single quotation mark (') or the double quotation mark ("). Use two consecutive double quotation marks ("") to represent a " character within a string delimited by double quotation marks. Similarly, use two consecutive single quotation marks ('') to represent a ' character within a string delimited by single quotation marks. A literal string is a constant and its contents are never modified when it is processed.

A literal string with no characters (that is, a string of length 0) is called a null string.

These are valid strings:

'Fred'
"Don't Panic!"
'You shouldn''t'        /* Same as "You shouldn't" */
''                      /* The null string         */

Note that a string followed immediately by a ( is considered to be the name of a function. If followed immediately by the symbol X or x, it is considered to be a hexadecimal string. If followed immediately by the symbol B or b, it is considered to be a binary string. Descriptions of these forms follow.

Implementation maximum: A literal string can contain up to 250 characters. (But note that the length of computed results is limited only by the amount of storage available.)

Hexadecimal Strings:

A hexadecimal string is a literal string, expressed using a hexadecimal notation of its encoding. It is any sequence of zero or more hexadecimal digits (0–9, a–f, A–F), grouped in pairs. A single leading 0 is assumed, if necessary, at the front of the string to make an even number of hexadecimal digits. The groups of digits are optionally separated by one or more blanks, and the whole sequence is delimited by single or double quotation marks, and immediately followed by the symbol X or x. (Neither x nor X can be part of a longer symbol.) The blanks, which can be present only at byte boundaries (and not at the beginning or end of the string), are to aid readability. The language processor ignores them. A hexadecimal string is a literal string formed by packing the hexadecimal digits given. Packing the hexadecimal digits removes blanks and converts each pair of hexadecimal digits into its equivalent character, for example: 'C1'X to A.

Hexadecimal strings let you include characters in a program even if you cannot directly enter the characters themselves. These are valid hexadecimal strings:

'ABCD'x
"1d ec f8"X
"1 d8"x

A hexadecimal string is not a representation of a number. Rather, it is an escape mechanism that lets a user describe a character in terms of its encoding (and, therefore, is machine-dependent). In EBCDIC, '40'X is the encoding for a blank. In every case, a string of the form '.....'x is simply an alternative to a straightforward string. In EBCDIC 'C1'x and 'A' are identical, as are '40'x and a blank, and must be treated identically.

Implementation maximum: The packed length of a hexadecimal string (the string with blanks removed) cannot exceed 250 bytes.

Binary Strings:

A binary string is a literal string, expressed using a binary representation of its encoding. It is any sequence of zero or more binary digits (0 or 1) in groups of 8 (bytes) or 4 (nibbles). The first group can have fewer than four digits; in this case, up to three 0 digits are assumed to the left of the first digit, making a total of four digits. The groups of digits are optionally separated by one or more blanks, and the whole sequence is delimited by matching single or double quotation marks and immediately followed by the symbol b or B. (Neither b nor B can be part of a longer symbol.) The blanks, which can be present only at byte or nibble boundaries (and not at the beginning or end of the string), are to aid readability. The language processor ignores them.

A binary string is a literal string formed by packing the binary digits given. If the number of binary digits is not a multiple of eight, leading zeros are added on the left to make a multiple of eight before packing. Binary strings allow you to specify characters explicitly, bit by bit.

These are valid binary strings:

'11110000'b        /* == 'f0'x                  */
"101 1101"b        /* == '5d'x                  */
'1'b               /* == '00000001'b and '01'x  */
'10000 10101010'b  /* == '0001 0000 1010 1010'b */
''b                /* == ''                     */

A note on binary string interpretation in TSO/E: Binary string support was introduced with TSO/E Version 2 Release 4. With this release, and all following ones, a string in the form of 'string'B causes string to be interpreted as binary string. Prior to TSO/E 2.4, the two parts of the expression 'string'B, string and B, were concatenated after the value for the variable B was determined. For example, if B='variable_value' were concatenated with string, then 'string'B would be interpreted as stringvariable_value. If this error is detected in REXX execs written before TSO/E 2.4, use the concatenation operator ( || ) to eliminate the problem. For example, code 'string'B as:

'string'|Lor.B

Symbols:

Symbols are groups of characters, selected from the:

• English alphabetic characters (A–Z and a–z¹)
• Numeric characters (0–9)
• Characters @ # $ ¢ . !² ? and underscore.
• Double-Byte Character Set (DBCS) characters (X'41'–X'FE')—ETMODE must be in effect for these characters to be valid in symbols.

Any lowercase alphabetic character in a symbol is translated to uppercase (that is, lowercase a–z to uppercase A–Z) before use.

These are valid symbols:

Fred
Albert.Hall
WHERE?

If a symbol does not begin with a digit or a period, you can use it as a variable and can assign it a value. If you have not assigned it a value, its value is the characters of the symbol itself, translated to uppercase (that is, lowercase a–z to uppercase A–Z). Symbols that begin with a number or a period are constant symbols and cannot be assigned a value.

One other form of symbol is allowed to support the representation of numbers in exponential format. The symbol starts with a digit (0–9) or a period, and it can end with the sequence E or e, followed immediately by an optional sign (- or +), followed immediately by one or more digits (which cannot be followed by any other symbol characters). The sign in this context is part of the symbol and is not an operator.

These are valid numbers in exponential notation:

17.3E-12
.03e+9

Implementation maximum: A symbol can consist of up to 250 characters. (But note that its value, if it is a variable, is limited only by the amount of storage available.)

Numbers:

These are character strings consisting of one or more decimal digits, with an optional prefix of a plus or minus sign, and optionally including a single period (.) that represents a decimal point. A number can also have a power of 10 suffixed in conventional exponential notation: an E (uppercase or lowercase), followed optionally by a plus or minus sign, then followed by one or more decimal digits defining the power of 10. Whenever a character string is used as a number, rounding may occur to a precision specified by the NUMERIC DIGITS instruction (default nine digits). See topics Numbers and arithmetic-Errors for a full definition of numbers.

Numbers can have leading blanks (before and after the sign, if any) and can have trailing blanks. Blanks might not be embedded among the digits of a number or in the exponential part. Note that a symbol (see preceding) or a literal string can be a number. A number cannot be the name of a variable.

These are valid numbers:

12
'-17.9'
127.0650
73e+128
' + 7.9E5 '

A whole number is a number that has a zero (or no) decimal part and that the language processor would not usually express in exponential notation. That is, it has no more digits before the decimal point than the current setting of NUMERIC DIGITS (the default is 9).

Implementation maximum: The exponent of a number expressed in exponential notation can have up to nine digits.

Operator Characters:

The characters: + - \ / % * | & = ¬ > < and the sequences >= <= \> \< \= >< <> == \== // && || ** ¬> ¬< ¬= ¬== >> << >>= \<< ¬<< \>> ¬>> <<= /= /== indicate operations (see topic Operators). A few of these are also used in parsing templates, and the equal sign is also used to indicate assignment. Blanks adjacent to operator characters are removed. Therefore, the following are identical in meaning:

345>=123
345 >=123
345 >= 123
345 > = 123

Some of these characters might not be available in all character sets, and, if this is the case, appropriate translations can be used. In particular, the vertical bar (|) or character is often shown as a split vertical bar.

Throughout the language, the not character, ¬, is synonymous with the backslash (\). You can use the two characters interchangeably according to availability and personal preference.

Special Characters:

The following characters, together with the individual characters from the operators, have special significance when found outside of literal strings:

,   ;   :   )   (

These characters constitute the set of special characters. They all act as token delimiters, and blanks adjacent to any of these are removed. There is an exception: a blank adjacent to the outside of a parenthesis is deleted only if it is also adjacent to another special character (unless the character is a parenthesis and the blank is outside it, too). For example, the language processor does not remove the blank in A (Z). This is a concatenation that is not equivalent to A(Z), a function call. The language processor does remove the blanks in (A) + (Z) because this is equivalent to (A)+(Z).

'REPEAT'   A + 3;

'REPEAT' A+3;