Remembering Ali Alpar's early work, and: three types of neutron stars?

Some memories of Ali Alpar and his early work are presented, with particular emphasis on his work on the origin of milliscond pulsars.
After this, arguments are summarized, indicating the existence of three categories of neutron stars, with two different formation mechanisms:
(i) A low‐mass category ( M∼1.25 ± 0.05 solar masses), characterized by low kick velocities. These neutron stars most probably formed by electron‐capture collapse in degenerate O‐Ne‐Mg cores of stars of initial masses between ∼8 and ∼11 solar masses.
(ii) An intermediate‐mass category (M∼1.40 ± 0.10 solar masses), characterized by high kick velocities. These stars formed by the collapse of the iron cores of stars with initial masses probably between ∼11 and ∼19 solar masses.
(iii) A category of massive neutron stars (M  ≥  1.70 solar masses), also characterized by high space velocities, and formed by the collapse of the iron cores, in this case of stars with intial masses >19 solar mases.