The magic of $$
If you put a label component on a form, then by default the name will become label_1:
In this case PHsPeed creates a class name "cust_detail_label_1". The main reason for this is that you can add other classes to this application. Suppose that you have selected a template with a header. This header can also contain a "label_1" which would cause a conflict when running code like:
$label_1->value='something'.
PHP will not be able to decide which variable to use and generates an error. So if PHsPeed generates a unique name adding the application name into: $cust_detail_label_1, then the valid syntax to assign a value to this label would be:
$cust_detail_label_1->value='myvalue';
But what if you decide for whatever reason, to rename your application? Then you must redo all your code as $cust_detail_label_1 will have become something different. Besides, if you have to prepend all your variables with the module name, then that becomes a lot of hard and boring work.
To overcome this, PHsPeed uses the $$ notation, which you can use for all the components that you have put on the form. So
$cust_detail_label_1->value='myvalue' will become $$label_1->value='myvalue';
The code generator will then append the module name while generating code, and if you rename the module, the generator will change the variable names accordingly.