Patent Claim confusion

[inle]

Hello;

The use claim is sometimes considered legit but sometimes considered as an inferential claim, I would like to know how to distinguish between a use claim and an inferential claim and when it is legit or not legit exactly. Lets take an example:

1. A lock including a rotor for receiving a key.

elements of the claimed invention include:
+ The lock; and
+ The rotor.
The key is NOT an element of the claimed invention. Thus this is an inferential claim (not legit) but how the meaning is interpreted because there is two possibilities :

+ First Possibility:

A lock including a rotor for receiving a key.

The lock include a rotor and the lock is used to receive a key.

+ Second Possibility:

A lock including a rotor for receiving a key.

The lock include a rotor and the rotor is used to receive a key.

Thank You

[Brad]

These are called "functional limitations" that are sometimes added to a claim.   From the USPTO MPEP:

I. INHERENCY AND FUNCTIONAL LIMITATIONS IN APPARATUS CLAIMS
Features of an apparatus may be recited either structurally or functionally. In re Schreiber, 128 F.3d 1473, 1478, 44 USPQ2d 1429, 1432 (Fed. Cir. 1997). See also MPEP https://www.uspto.gov/web/offices/pac/mpep/s2114.html