Set Analysis Question - fields placed in without any equal sign, what does that do?

[benvatvandata]

I noticed an expression:

sum( {$<
[Item Code] = [Estimate Master Item Code],
[Estimate Master Item Code],
[Estimate Material Code],
[LinkId] = {"JOB"},
[Plant] =
>}
[JobLine Ordered Quantity]
)

Can someone tell me what having [Estimate Master Item Code], [Estimate Material Code] (without equal signs after them) in there does? is that similar to what [Plant]= is doing? 

The way this object is working seems weird... the only dimension is JobCode btw.

[Or · Accepted solution]

Looks to me like you have it right - it seems to be an undocumented version of ignoring selections in this field, same as Field= , or at least that's how it behaves in any scenario I've tested it in