From OpenSCADAWiki
The language uses the implicit definition of local variables, which is to define a new variable in the case of assigning a value to it. This type of local variable is set according to the type of the assigning value. For example, the expression Qr=Q0*Pi+0.01; will define Qr variable with the type of variable Q0. And with implementing the built-in functions, there also added the statement var for defining the variables in the function scope instead global one.