Inner part of the asteroid main belt shown in projection onto the plane of the proper semimajor axis a and the proper sine of inclination sinI. Our working definition of the inner part is a< 2.5 au, the position of the 3/1 mean motion resonance with Jupiter, and we also exclude here the high-inclination population of Phocaeas. The dashed line indicates the approximate location of the ν₆ secular resonance. Black symbols indicate prograde-rotating objects from the study of Kryszczyńska (2013), and the three objects discussed in Sect. 3 are labeled. The open symbol shows the location of (20) Massalia, the largest member of its own family.