How to use a foreign key as a part of a composite primary key in Entity Framework?

I've got an entity which is identified by no own id but an unique combination of properties, each of which is a foreign key.

But Entity Framework designer does not seem to allow to make a foreign key (a "navigation property") 开发者_开发知识库a part of a primary key. Am I misunderstanding something or is it just unsupported?

Example:

here an instrument is designated by a very short symbolic identifier (name), which doesn't seem to be wise to be replaced by a numeric code.

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Navigation properties cannot be part of primary key. Composite primary key (entity key) can consists only from scalar properties -> only foreign properties related to these navigation properties can be part of FK - here is the example of the model which uses such relation.