Classification: ref-only. However, this version needs to match the version dotnet/sdk uses, where it's classified as needing to be built from source.

https://github.com/dotnet/core-setup/blob/e7a4af00bc679e065308da07bfddfdd43b930161/src/managed/Microsoft.NET.HostModel/Microsoft.NET.HostModel.csproj#L11-L13

Mail thread excerpt:

[@dseefeld] Do you think there’s something in 1.5.0 that is necessary? I have 1.3.0, 1.4.1 and 1.4.2 already as ref packages and will be adding 1.6.0. This is the only place 1.5.0 is being used.

[@swaroop-sridhar] The HostModel uses PEReader from System.Reflection.MetaData.
As far as I can tell, other versions of System.Reflection.MetaData listed below should work fine.

I think we chose the version of System.Reflection.MetaData to match what’s in the SDK.
@nguerrera do you anticipate any problems if we change the version to 1.6.0?

[@nguerrera] For host model, this should be reference only. The real use of it as non-reference only is in dotnet/sdk, where we package it into the net46 build task though. We used to just exclude the net46 build task from source build, but it turns out vs code on RedHat uses it ☹

The version used by core-setup for HostModel cannot exceed the version used by dotnet/sdk.

[@nguerrera] It actually needs to be the same version as dotnet/sdk due to binding redirect issues with msbuild tasks on full framework.