Is there any way to distinguish a non-constant field and a constant field" at compile time in c#?

I am currently developing c# Code Analysis (FxCop) rules to check the developers' code for inconsistency in naming. 

What I have been looking for is a way to target only constant fields. But how are they declared when compiled? Is there like a flag (I have been looking into "HasDefault", but this didn't give me much information).

I am using the FxCop-API (FxCopSdk.dll & Microsoft.Cci.dll). No Reflection is used.

Summing up: How can I distinguish a non-constant field from a constant field with Code Analysis(FxCop), and how can I target the constant.