one of up to 153 aircraft configured with 71-76 passenger seats and certificated in the United States with a maximum gross takeoff weight of 86,000 pounds or less (“76- seat aircraft”).
Exception one: If the Company establishes a fleet of new small narrowbody aircraft, the number of permitted 76-seat aircraft may increase on a one 76-seat aircraft for each one and one quarter new small narrowbody aircraft (1:1.25) ratio (rounded to the closest integer) up to a total of 223 76-seat aircraft. In the event more than 153 76- seat aircraft are in category A or C operations, then on January 1, 2014, and each succeeding January 1 thereafter, the Company will implement its plan to reduce the number of 50-seat aircraft in category A or C operations below 348 (the number 50-seat aircraft in category A or C operations as of July 1, 2012) rounded to the closest integer, as follows:
1) 2.7 50-seat aircraft for each of the first additional ten 76-seat aircraft (above 153),
2) 2.7 50-seat aircraft for each of the next additional ten 76-seat aircraft (above 163),
3) 2.8 50-seat aircraft for each of the next additional ten 76-seat aircraft (above 173),
4) 2.9 50-seat aircraft for each of the next additional ten 76-seat aircraft (above 183),
5) 3.0 50-seat aircraft for each of the next additional ten 76-seat aircraft (above 193).
6) 3.1 50-seat aircraft for each of the next additional ten 76-seat aircraft (above 203), and
7) 4.6 50-seat aircraft for each of the next additional ten 76-seat aircraft (above 213).
Note one: Upon the delivery of a 223rd 76-seat aircraft, the number of permitted 50-seat aircraft will be 125 regardless of the number otherwise provided in Section 1 b. 46. f. Exception one.
Note two: If on January 1, 2014, or any succeeding January 1 thereafter, the number of 50-seat aircraft in category A or C operations exceeds the maximum permitted number, the Company will require carriers that engage in category A or C operations to suspend or cease operations on a sufficient number of 50-seat aircraft or 76-seat aircraft to comply with these requirements within 60 days and to remain in compliance thereafter. The Company will be excused from compliance with the provisions of this Note in the event a circumstance over which the Company does not have control is the cause of such non-compliance.

Definition 28: “Fleet” means aircraft in service, undergoing maintenance, and operational spares.
Here is the language in Definitions. If they ESTABLISH this category, then they can is how this reads.