ECN Forum Forums Code Related Discussion NEC & other Code issues Chapter 9 Table 8 Conversions Missing

In Chapter 9, table 8 of the NEC I'm
curious as to why the conversions from mm2 to Circular mils are missing for wire sizes 250MCM to 2000MCM. It's easy to do the conversions but can't figure why they are left out. Also 250.122(B) Says to use the circular mil area of the conductor for proportionate upsizing. If it's proportionate then what's the reason for not using mm2 figures in the calculations?