How do you only update NuGet packages with certain IDs?

According to the NuGet documentation: Update Command Update packages to latest available versions. This command also updates NuGet.exe itself. Usage `nuget update <packages.config|solution>` Options: Id - Package ids to update. This says that the ID option is the package IDs to update. How do you provide multiple ID's? This works: ``` NuGet.exe update "MySln.sln" -RepositoryPath "MyRepoPath" -id Ref1 ``` ...but how do you also udpate Ref2? This fails: ``` NuGet.exe update "MySln.sln" -RepositoryPath "MyRepoPath" -id Ref1,Ref2 ``` I am trying to update a subset of packages and prevent the need for a large number of calls to NuGet.exe.