An expression is something that has some value (variable, constant) or returns some value as result of function call (e.g., Func(a b)) or calculation with operators (e.g., a + b).
You can assign expressions to variables (variable = expression), return from functions (ret expression), use expressions as arguments of commands/functions, and as parts of other expressions. Expressions that contain operators and spaces must be enclosed in parentheses when passing to a function.
a = 10 b = a s = "string" a = b + (c * 5) - 1 def C5 (c * 5) a = b + C5 - 1 a = Func(b c) a = Func2(b 1.5 (c + 1) Func(d 10) s) a = Func2(b 1.5 c+1 Func(d 10) s) ret a + 10 out Func(a b)
Here a, b, c, d and s are variables; Func and Func2 are functions.