Comprehensive rules for variables, constants, and literal strings are contained in the Open Object Rexx: Reference .
Rexx imposes few rules on variable names. A variable name can be up to 250 characters long, with the following restrictions:
The variable name can be typed and queried in uppercase, mixed-case, or lowercase characters. A variable name in uppercase characters, for example, can also be queried in lowercase or mixed-case characters. Rexx translates lowercase letters in variables to uppercase before using them. Thus the variables names " abc", "Abc", and "ABC" all refer to the single variable "ABC". If you reference a variable name that has not yet been set, the name, in uppercase, is returned.
Literal strings in Rexx are delimited by quotation marks (either ' or "). Examples of literal strings are:
If you need to use quotation marks within a literal string, use quotation marks of the other type to delimit the string. For example:
|'He said, "Bother"'|
There is another way to do this. Within a literal string, a pair of quotation marks of the same type that starts the string is interpreted as a single character of that type. For example:
|'Don''t panic' (same as "Don't panic" )|
|"He said, ""Bother""" (same as 'He said, "Bother"')|