Natura - nature
   actualia - actual entities
     Mundus Plinius - physical world
       particles
         hadrons - composite particles
           mesons - bosonic hadrons
             light unflavored mesons
               01.1 =π^+ - positive pion
               01.2 =π^- - negative pion
               02 =π^0 - neutral pion
               03 η
               04 =f_0(600)
               05.1 =ρ(770)^+
               05.2 =ρ(770)^-
               05.3 =ρ(770)^0
               06 ω(782)
               07 η'(958)
               08 =f_0(980)
               09.1 =a_0(980)^+
               09.2 =a_0(980)^-
               09.3 =a_0(980)^0
               10 φ(1020)
               11 =h_1(1170)
               12.1 =b_1(1235)^+
               12.2 =b_1(1235)^-
               12.3 =b_1(1235)^0
               13.1 =a_1(1260)^+
               13.2 =a_1(1260)^-
               13.3 =a_1(1260)^0
               14 =f_2(1270)
               15 =f_1(1285)
               16 η(1295)
               17.1 =π(1300)^+
               17.2 =π(1300)^-
               17.3 =π(1300)^0
               18.1 =a_2(1320)^+
               18.2 =a_2(1320)^-
               18.3 =a_2(1320)^0
               19 =f_0(1370)
               20.1 =π_1(1400)^+
               20.2 =π_1(1400)^-
               20.3 =π_1(1400)^0
               21 η(1405)
               22 =f_1(1420)
               23 ω(1420)
               24.1 =a_0(1450)^+
               24.2 =a_0(1450)^-
               24.3 =a_0(1450)^0
               25.1 =ρ(1450)^+
               25.2 =ρ(1450)^-
               25.3 =ρ(1450)^0
               26 η(1475)
               27 =f_0(1500)
               28 =f'_2(1525)
               29.1 =π_1(1600)^+
               29.2 =π_1(1600)^-
               29.3 =π_1(1600)^0
               30 =η_2(1645)
               31 ω(1650)
               32 =ω_3(1670)
               33.1 =π_2(1670)^+
               33.2 =π_2(1670)^-
               33.3 =π_2(1670)^0
               34 φ(1680)
               35.1 =ρ_3(1690)^+
               35.2 =ρ_3(1690)^-
               35.3 =ρ_3(1690)^0
               36.1 =ρ(1700)^+
               36.2 =ρ(1700)^-
               36.3 =ρ(1700)^0
               37 =f_0(1710)
               38.1 =π(1800)^+
               38.2 =π(1800)^-
               38.3 =π(1800)^0
               39 =φ_3(1850)
               40.1 =π_2(1880)^+
               40.2 =π_2(1880)^-
               40.3 =π_2(1880)^0
               41 =f_2(1950)
               42 =f_2(2010)
               43.1 =a_4(2040)^+
               43.2 =a_4(2040)^-
               43.3 =a_4(2040)^0
               44 =f_4(2050)
               45 =f_2(2300)
               46 =f_2(2340)