Compiler Error CS1679
Invalid extern alias for '/reference'; 'identifier' is not a valid identifier
When using the external assembly alias feature of the /reference option, the text that follows /reference: and that precedes the '=' must be a valid C# identifier or keyword according to the C# Language Specification.
To correct this error, change text before the "=" to a valid C# identifier or keyword.
Example
The following example generates CS1679.
// CS1679.cs
// compile with: /reference:123$BadIdentifier%=System.dll
class TestClass {
static void Main()
{
}
}