What does this line mean in C# r => r.Item1?

Question

r => r.Item1 == dFName

Its part of this line

dFName = PropertyUtil.GetName<kUpdate>(r => r.Resolution);
fld2Lup = map.DTField2LookupMap[domType].First(r => r.Item1 == dFName );

Answer 1

That is essentialy..

Return the First item of the "DTField2LookupMap[domType]" collection where the items property "Item1" is equal to dfName

this is a lambda expression: https://msdn.microsoft.com/en-us/library/bb397687.aspx