This is a paragraph from a programming language book:
It's important to know that C# cannot exist alone; after all, it's a language that runs on variants of .NET. In theory, someone could write a compiler for C# that uses a different platform, with different underlying types. In practice, the platform for C# is .NET, which provides tens of thousands of types to C#, including System.Int32, which is the C# keyword alias int maps to, as well as many more complex types, such as System.Xml.Linq.XDocument
I want to know what is the role of "to" in which is the C# keyword alias int maps to grammatically and also what does the word "to" refer to?