The following are the relevant commands:
DEFINE SYMBOL symbol_name = string
SHOW SYMBOL/ALL SHOW SYMBOL symbol_name SHOW SYMBOL partial_name
CANCEL SYMBOL/ALL CANCEL SYMBOL symbol_name
Legal symbol names must begin with a letter and contain only letters, digits, underscores, and dollar signs.
yes? DEFINE SYMBOL hi = hello everyone yes? MESSAGE ($hi) ! issues "hello everyone" msg
It is also possible to nest symbol definitions, as the following commands illustrate:
yes? DEFINE SYMBOL label_2 = My test label yes? DEFINE SYMBOL number = 2 yes? SAY ($label_($number)) My test label