The Mathematica package context for the .NET/Link support functions.
Using this is preferable to hard-coding "NETLink`" in your code if you need to explicitly load the .NET/Link package file.
BAD: ml.Evaluate("Needs[\"NETLink`\"]"); GOOD: ml.Evaluate("Needs[\"" + NETLinkConstants.PACKAGE_CONTEXT + "\"]");
NETLinkConstants Class | Wolfram.NETLink Namespace