What does "+1" mean in the following Qlik expression

I am assuming the following expression means sum of sales for year 2009 and country Sweden, but I am not sure why +1 is being used, is it used as separator or it has any special meaning?

Sum({$<Year={2009}>+1<Country={'Sweden'}>} Sales)

1 in set analysis indicates that the calculation will ignore all selections made - returns a full set of data irrespective of user selections

In your case I can read the calculation like this:

Give me the union sum of Sales for:

• Year={2009} - all sales for 2009. Respect the selections made (apart from Year)
• 1<Country={'Sweden'} - sales for Sweden but as if there are no selections applied across the app (if there are any selections made - ignore them)

Helpful links:

• Set Modifiers (scroll down to Forced exclusion section)
• Set analysis and set expressions (scroll down to Operators section)