The Universal World Owner's Manual

Value controls provide an interface that lets the user select a value which is then provided to your script when they press a button. Setting up a value control requires you to provide initial, minimum and maximum values. Getting the resulting value back to your script is done using a reference to the name of the value control which is made using the & symbol. Here is a 'simple' example:

$itemNum = 40
$initialVal = 10
$minVal = 0
$maxVal = 20

osdcreate(OSDBUILDING,"ExampleOSD", "Example" ) 
osdadd(TEXTRIGHT, 340, 134, 0, 0, "", "Select amount:") 
osdadd(VALUE, 350, 130, 100, 25, "numgoods", "$initialVal|$minVal|$maxVal") 

osdadd(EXITBUTTON, 150, 200,300,40, "Export|$itemNum|&numgoods", "Select") 
osdactivate() 

In this example, when the user clicks 'Select' they're triggering the 'Export' EXITBUTTON with two parameters, the first being '$itemNum' (i.e. 40), and the second being whatever value they've entered in the “numgoods” control. i.e.

Event( "OSDSelect", "ExampleOSD:Export" )
{
    $itemNum = $gParam[1]
    $valueSelected = $gParam[2]
    
    ...
}