What is the "=> " within an set expression?

[Applicable88]

Hello,

I have a following if-statement:

= IF(
'$(Unit)' = 'LL',
Sum({<[Type]={"IST"},[Structure.Sales]=>}[Value]),

if(

'$(Unit)' = 'GG'
Sum({<[Type]={"Should"},[Structure.Sales]=>}[Value]))))

Normally after the fielname you would have another pair curvy brackets telling you what to filter in "Structure.Sales"

But now I seen this "=> " at the end of the set expression .....what does it mean?

Thank you in advance.

Best. 

[Taoufiq_Zarra · Accepted solution]

@Applicable88 

=> are in fact two parts

     >is the end of the < :    <[Type]={"IST"},[Structure.Sales]=>

    = ignore selection in the [Structure.Sales] field