# -refout (C# Compiler Options)

The -refout option specifies a file path where the reference assembly should be output. This translates to metadataPeStream in the Emit API. This option corresponds to the ProduceReferenceAssembly project property of MSBuild.

## Syntax

-refout:filepath


## Arguments

filepath The filepath for the reference assembly. It should generally match that of the primary assembly. The recommended convention (used by MSBuild) is to place the reference assembly in a "ref/" sub-folder relative to the primary assembly.

## Remarks

Metadata-only assemblies have their method bodies replaced with a single throw null body, but include all members except anonymous types. The reason for using throw null bodies (as opposed to no bodies) is so that PEVerify could run and pass (thus validating the completeness of the metadata).

Reference assemblies include an assembly-level ReferenceAssembly attribute. This attribute may be specified in source (then the compiler won't need to synthesize it). Because of this attribute, runtimes will refuse to load reference assemblies for execution (but they can still be loaded in reflection-only mode). Tools that reflect on assemblies need to ensure they load reference assemblies as reflection-only, otherwise they will receive a typeload error from the runtime.

• A reference assembly only has references for what it needs in the API surface. The real assembly may have additional references related to specific implementations. For instance, the reference assembly for class C { private void M() { dynamic d = 1; ... } } does not reference any types required for dynamic.
The -refout and -refonly options are mutually exclusive.