Zener diode minimum and maximum current
Test currents relate to impedances stated to the right of these figures. For instance, for the 1N5221 there are two test currents listed and these are 20 mA and 0.25 mA and these relate to the maximum dynamic impedances stated in columns to the right (30 ohms and 1200 ohms). Nothing perculiar about this at all.

Those test currents ARE NOT \$I_{ZMAX}\$ or \$I_{ZMIN}\$. 

The test currents are \$I_{ZT1}\$ and \$I_{ZT2}\$: -